Multifunctional light-cured 3D printing device based on DMD and its construction method

Abstract

The application discloses a multifunctional light-curing 3D printing device based on a DMD and a construction method thereof, and belongs to the field of optical experimental auxiliary structure devices. The multifunctional light-curing 3D printing device based on the DMD is obtained through the construction method. The multifunctional light-curing 3D printing device based on the DMD and the construction method thereof can realize four types of functions, i.e. up-projection 3D printing, down-projection 3D printing, side-projection 3D printing and volume-rotation-projection printing, and the construction method of the system is simple, flexible and highly designable, and can be used for preparing various target sizes. The double-light-source focusing method is adopted, the focusing can be conveniently adjusted by using an illumination light source, and the printing interface can be observed in real time. According to different printing requirements, the combined double-telecentric projection lens group is adopted, the rear projection lens group can be conveniently disassembled, and various printing requirements can be met.

Description

Technical Field

[0001] This invention belongs to the field of optical experimental auxiliary structure equipment, specifically relating to a multifunctional photopolymerization 3D printing device based on DMD and its construction method. Background Technology

[0002] 3D printing is a type of additive manufacturing technology. It is a technique that uses a digital model as a basis and employs curable resin, powdered metal, or plastic and other bondable materials to construct objects layer by layer or point by point. Among various printing technologies, digital maskless printing technology, which uses a digital micromirror device (DMD) as a spatial light modulator, has advantages such as high printing speed and high printing accuracy.

[0003] To address diverse printing needs, various DMD-based photopolymerization printing systems have emerged, such as top projection printing systems, bottom projection printing systems, volume rotation printing systems, and side projection printing systems. However, each system has its own advantages and disadvantages, and systems are generally not interchangeable. For example, in bottom projection printing systems, gravity exerts a force on the printing material during the movement of the z-axis platform, affecting the printing results, thus requiring careful material selection. While top projection printing systems are free from gravity, they can form air bubbles during printing and have difficulty leveling when the printing fluid is highly viscous. Side projection printing systems balance the advantages and disadvantages of top and bottom projection printing; although gravity has some influence, air bubbles rise automatically during printing, and there are no leveling issues.

[0004] Currently, the projection lens of traditional 3D printing equipment is integrated. To expand the functionality of the equipment, optical components such as beam splitters and dichroic mirrors need to be added. These new components can only be placed between the lens and the DMD (Digital Modulator-Distributor) or between the lens and the printing stand. This placement method introduces aberrations into the optical path, reducing print quality. Furthermore, due to limited design space, it hinders multi-functional expansion and combinations. Replacing the lens requires adjusting the entire system's optical path, resulting in poor flexibility and potential interference with other functional components. Consequently, the same printing system can only produce fixed-size components, preventing multi-scale and multi-functional processing. Summary of the Invention

[0005] The technical problem this invention aims to solve is to provide a multifunctional photopolymer 3D printing device based on a DMD projection system, capable of four types of functions: downward projection 3D printing, upward projection 3D printing, side projection 3D printing, and volumetric rotational projection printing; and a method for constructing the multifunctional photopolymer 3D printing device based on the DMD. Without changing the main optical path, various 3D printing needs can be met by replacing different printing modules. The device has a simple structure, relatively low cost, and offers great flexibility and a wide production range.

[0006] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0007] This invention proposes a method for constructing a multifunctional photopolymerization 3D printing device based on DMD, the method comprising the following steps:

[0008] Step 1: Installation of the main optical path module

[0009] ① Determine the installation location and angle of the DMD spatial light modulator;

[0010] ② Determine the position and angle of the front projection lens group and the beam splitter. The beam splitter, the front projection lens group and the DMD spatial light modulator are set in sequence and the three are on the same optical axis.

[0011] ③ Determine the position of mirror I so that the reflected light from mirror I can be incident on the center of the DMD spatial light modulator and the angle between it and the optical axis of the main optical path is 24°. The main optical path is formed by the light from the DMD spatial light modulator, through the front projection mirror group, and through the beam splitter to the rear projection mirror group. A dichroic mirror is installed on the incident light path of mirror I. A rear condenser mirror group is installed between the dichroic mirror and mirror I, and the three are on the same optical axis.

[0012] ④ Install a 405nm LED light source and a 530nm LED light source I on both sides of the dichroic mirror. The output ends of the 405nm LED light source and the 530nm LED light source I are respectively connected to a light homogenizing device. A front collimating lens group is installed between the two light homogenizing devices and the dichroic mirror. After the output light of the 405nm LED light source and the 530nm LED light source I is homogenized by the light homogenizing device and collimated by the front collimating lens group, it is combined by the dichroic mirror. The combined collimated light is then directed into the rear condenser lens group, and after passing through the rear condenser lens group, it is directed into the DMD spatial light modulator through the reflector I. A transducer is set on the reflected light path of the beam splitter prism, and a CCD camera is installed on the light path after the transducer. This completes the assembly of the main optical path module.

[0013] Step 2: Installation of the four printing function modules

[0014] Install a projection printing module on top of the main optical path module:

[0015] The position and angle of the rear projection mirror group I are determined. The rear projection mirror group I, the beam splitter, the front projection mirror group, and the DMD spatial light modulator are sequentially set on the same optical axis. The rear projection mirror group I is set in the transmission light path of the beam splitter.

[0016] An automatic large-stroke XY moving platform I is mounted on an optical platform via an automatic large-stroke XY moving platform fixed base I. A detachable Z-axis lifting platform I is mounted on the automatic large-stroke XY moving platform I via a Z-axis lifting platform bracket I. A manual Z-axis moving platform is mounted directly above the automatic large-stroke XY moving platform I and directly below the optical axis of the rear projection lens group I. A projection printing box is mounted above the manual Z-axis moving platform, allowing the vertical position of the upper projection printing box to be adjusted via the manual Z-axis moving platform. The Z-axis printing platform is connected to the Z-axis lifting platform I, and a projection printing substrate is mounted on the Z-axis printing platform. By adjusting the position of the Z-axis lifting platform I, the Z-axis printing platform and the upper projection printing substrate are placed into the upper projection printing box, ensuring that the focal plane is on the upper projection printing substrate.

[0017] Install the projection printing module on top of the main optical path module:

[0018] The position and angle of the rear projection lens group II are fixed to ensure that the CCD camera, adapter lens, beam splitter, and rear projection lens group II share the same optical axis, and that the rear projection lens group II is positioned on the reflected light path of the beam splitter. An automatic large-stroke XY moving platform II is mounted on the optical platform via an automatic large-stroke XY moving platform fixing base II. A lower projection printing box and a Z-axis lifting stage II are mounted on the automatic large-stroke XY moving platform II, and a lower projection printing substrate is mounted on the Z-axis lifting stage II. The Z-axis lifting stage II, along with the lower projection printing substrate, is inserted into the lower projection printing box, ensuring that the focal plane is on the lower projection printing substrate. A reflector II is installed on the output light path of the rear projection lens group II. The positions of the reflector II, Z-axis lifting stage II, and lower projection printing substrate are adjusted so that the focal plane is on the lower projection printing substrate and centered on the automatic large-stroke XY moving platform II.

[0019] Install a volume rotation projection printing module on top of the main optical path module:

[0020] The position and angle of the rear projection lens group I are kept the same as those of the rear projection lens group I in the upper projection printing module. An automatic large-stroke XY moving platform II is installed on the optical platform via an automatic large-stroke XY moving platform fixed base II. A Z-axis lifting stage II is installed on the automatic large-stroke XY moving platform II. The side projection substrate is installed on the Z-axis lifting stage II via a side projection substrate lifting bracket. The side projection printing box is installed on the automatic large-stroke XY moving platform II via a side projection printing box base. A reflecting prism is installed in the output light path of the rear projection lens group I. The positions of the reflecting prism, the Z-axis lifting stage II, and the side projection substrate are adjusted so that the focal plane is on the side projection substrate and is located at the center of the automatic large-stroke XY moving platform II.

[0021] Install a volume rotation projection printing module on top of the main optical path module:

[0022] The position and angle of the rear projection lens group II are kept the same as those of the rear projection lens group II in the lower projection printing module. The position and angle of the illumination lens group are fixed in the output light path of the rear projection lens group II, and a 530nm LED light source II is installed behind the illumination lens group. A lifting turntable and a lifting turntable controller are installed in the light path of the illumination lens group and the beam splitter. A lifting turntable controller 28 is installed on the lifting turntable 27. The rotating printing box is installed below the lifting turntable, and the height of the lifting turntable is adjusted to the focal plane exposure position corresponding to the rear projection lens group II through the lifting turntable controller.

[0023] Furthermore, step 1 ① includes:

[0024] A mechanical mounting bracket for fixing the main optical path and collimating laser I are installed on an optical platform. A laser receiving plane is installed on the end face of the collimating laser I on the side of the emitted light to receive the reflected light from the collimating laser I. The vertical plane of the mechanical mounting bracket is polished and serves as the standard surface for assembly. A circular through-hole is opened in the center of the standard surface for installing and fixing the DMD spatial light modulator. The position of the horizontal plane of the mechanical mounting bracket is adjusted using a level to ensure that the laser beam emitted from the collimating laser I reaches the standard surface at the end of the mechanical mounting bracket and passes through the center of the circular through-hole. The reflecting mirror III is tightly fitted to the surface of the standard surface, so that the normal of the reflecting mirror III and the standard surface are aligned. The collimating laser I and the mechanical mounting bracket are then adjusted. The relative positions of the frames are adjusted so that the laser receiving plane can receive the reflected light spot of collimated laser I, ensuring that the laser can be reflected by mirror III. The angle of the mechanical fixing frame is adjusted by shims to make the reflected light spot on the laser receiving plane coincide with the emitted light spot of collimated laser I. After confirming that the light spots coincide, mirror III is removed, and a DMD spatial light modulator is installed in the original position of mirror III. This ensures that the laser optical axis and the reflection plane of the DMD spatial light modulator are completely perpendicular, and that the laser can illuminate the center position of the DMD spatial light modulator. The angle of the DMD spatial light modulator is adjusted again by shims to make the reflected light spot on the laser receiving plane coincide with the emitted light spot of collimated laser I.

[0025] Furthermore, step 1, ② includes:

[0026] Install the front projection mirror assembly on the mechanical mounting bracket, ensuring it is in the optical path of the collimated laser I and the DMD spatial light modulator. Install the reflector III on the side of the front projection mirror assembly closest to the collimated laser I, ensuring the optical axis of the front projection mirror assembly is perpendicular to the surface of the reflector III. Adjust the angle of the front projection mirror assembly so that the reflected light spot on the laser receiving plane coincides with the emitted light spot of the collimated laser I. After confirming the light spot coincidence, fix the position and angle of the front projection mirror assembly using the mechanical mounting bracket and remove the reflector III. Set a beam splitter prism in the optical path of the emitted light from the front projection mirror assembly. Adjust the angle of the beam splitter prism so that the reflected light spot obtained by the beam splitter prism surface on the laser receiving plane coincides with the emitted light spot of the collimated laser I. Fix the position and angle of the beam splitter prism using the mechanical mounting bracket.

[0027] Furthermore, step 1, ③ includes:

[0028] A collimated laser II is mounted on an optical platform, and a laser receiving plane is installed on the end face of the collimated laser II's output light side to receive the reflected light. A reflecting mirror I is mounted on a mechanical mounting frame. The relative position and height of the collimated laser II and the reflecting mirror I are adjusted so that the output light of the collimated laser II can be received and reflected by the reflecting mirror I. By adjusting the angle of the reflecting mirror I, the reflected light of the collimated laser II can be incident on the center position of the DMD spatial light modulator, with an angle of 24° to the main optical path axis. A dichroic mirror is installed along the optical path using a mechanical mounting bracket. The angle of the dichroic mirror is adjusted using shims so that the light emitted from collimated laser II, after being reflected by the surface of the dichroic mirror, coincides with the reflected light spot on the laser receiver plane. A rear condenser lens assembly is installed along the optical path of the dichroic mirror and reflector I using a mechanical mounting bracket. A reflector III is installed on the end face of the rear condenser lens assembly near the collimated laser II. The angle of the rear condenser lens assembly is adjusted so that the light beam emitted from collimated laser II, after being reflected by reflector III, coincides with the original emitted light spot on the laser receiver plane.

[0029] Furthermore, in step 1, ④, the specific operation process of setting a transducer in the reflected light path of the beam splitter and installing a CCD camera in the light path after the transducer is as follows:

[0030] Keep collimating laser I on. Set up a transition mirror in the optical path between the beam splitter and the collimating laser I. Install a reflector III on the end face of the transition mirror near the beam splitter, ensuring that the optical axis of the transition mirror is perpendicular to the surface of the reflector III. Adjust the angle of the transition mirror so that the reflected light spot on the laser receiving plane coincides with the light spot emitted by the collimating laser I. After confirming that the light spots coincide, fix the position and angle of the transition mirror, remove the reflector III, and install a CCD camera in the optical path after the transition mirror.

[0031] Furthermore, during the installation of the upper projection printing module and the side projection printing module, the process of determining the position and angle of the rear projection lens group I is as follows:

[0032] Install the rear projection mirror assembly I on the mechanical mounting bracket, ensuring it is in the optical path of the collimated laser I and the DMD spatial light modulator. Install the reflector III on the side of the rear projection mirror assembly I closest to the collimated laser I, ensuring the optical axis of the rear projection mirror assembly I is perpendicular to the surface of the reflector III. Adjust the angle of the rear projection mirror assembly I so that the light spot obtained by the reflection of the light emitted from the collimated laser I through the center of the reflector III coincides with the light emitted from the collimated laser I. After confirming that the light spots coincide, fix the position and angle of the rear projection mirror assembly I and remove the reflector III.

[0033] Furthermore, the specific steps of installing the projection printing module on top of the main optical path module include:

[0034] With collimating laser I on, install mirror III on the side of the front projection lens group closest to collimating laser I, so that the laser beam is reflected by mirror III to obtain the reflected light path of the beam splitter. Install collimating laser III on the optical platform, aligning its output light axis with the optical axis of the beam splitter's reflected light path obtained from collimating laser I. After confirming that the two optical axes coincide, remove mirror III from the side of the front projection lens group closest to collimating laser I. Install rear projection lens group II in the optical path of collimating laser III and beam splitter using a mechanical mounting bracket. Install mirror III on the side of rear projection lens group II closest to collimating laser I, ensuring that the optical axis of rear projection lens group II is perpendicular to the surface of mirror III. Adjust the angle of rear projection lens group II so that the light spot obtained by the reflection of the collimating laser III's output light through the center of mirror III coincides with the output light spot of collimating laser III. After confirming that the light spots coincide, fix the position and angle of rear projection lens group II and remove mirror III.

[0035] An automatic large-stroke XY moving platform II is installed on an optical platform via an automatic large-stroke XY moving platform fixed base II. A lower projection printing box and a Z-axis lifting stage II are installed on the automatic large-stroke XY moving platform II. A lower projection printing substrate is installed on the Z-axis lifting stage II. The Z-axis lifting stage II, together with the lower projection printing substrate, is inserted into the lower projection printing box, ensuring that the focal plane is on the lower projection printing substrate. The collimating laser III is removed, and a reflector II is installed on the output optical path of the rear projection lens group II. The positions of the reflector II, the Z-axis lifting stage II, and the lower projection printing substrate are adjusted so that the focal plane is on the lower projection printing substrate and is centered on the automatic large-stroke XY moving platform II.

[0036] Furthermore, in the operation of installing the volumetric rotation projection printing module based on the main optical path module, the specific operation process of fixing the position and angle of the illumination lens group on the output optical path of the projection lens group II is as follows:

[0037] An illumination mirror assembly is installed in the optical path of the collimating laser III and the beam splitter using a mechanical mounting bracket. A reflector III is installed on the side of the illumination mirror assembly closest to the collimating laser III, ensuring that the optical axis of the illumination mirror assembly is perpendicular to the surface of the reflector III. The angle of the illumination mirror assembly is adjusted so that the light spot obtained by reflecting the light emitted from the collimating laser III through the center of the reflector III coincides with the emitted light spot. After confirming that the light spots coincide, the position and angle of the illumination mirror assembly are fixed, and the reflector III is removed.

[0038] The present invention also proposes a multifunctional photopolymer 3D printing device based on DMD, which is constructed using the above-mentioned construction method of the multifunctional photopolymer 3D printing device based on DMD.

[0039] Through the above design scheme, the present invention can bring the following beneficial effects: The device constructed by the DMD-based multifunctional photopolymerization 3D printing device construction method proposed in this invention can realize four types of functions: top projection 3D printing, bottom projection 3D printing, side projection 3D printing, and volume rotation projection printing. Furthermore, the construction method proposed in this invention results in a simple, flexible, and highly designable printing device structure, capable of producing various target sizes. A dual-light source focusing method is adopted, allowing for convenient focusing using the illumination source and real-time observation of the printing interface. For different printing needs, this invention employs a combined dual telecentric projection lens group, which allows for easy disassembly of the rear projection lens group to change the projection resolution. Attached Figure Description

[0040] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to understand the invention. They do not constitute an improper limitation of the invention. In the drawings:

[0041] Figure 1 A schematic diagram showing the assembly of the DMD spatial light modulator as determined by mirror III;

[0042] Figure 2 This is a schematic diagram of the assembly of a DMD spatial light modulator;

[0043] Figure 3 This is a schematic diagram of the front projection lens assembly.

[0044] Figure 4 This is a schematic diagram of the assembly of the beam splitter prism;

[0045] Figure 5 This is an assembly diagram showing how the light source optical path is determined by a laser in the main optical path module.

[0046] Figure 6 This is an assembly diagram of a 405nm LED light source, a 530nm LED light source I, a front collimating lens group, and a dichroic mirror;

[0047] Figure 7 A schematic diagram of the optical path of a dual telecentric projection lens;

[0048] Figure 8 A schematic diagram showing the position of the CCD camera and rear projection lens group II determined by a laser;

[0049] Figure 9 This is a schematic diagram of the upper projection printing module assembly;

[0050] Figure 10 This is a schematic diagram of the lower projection printing module assembly;

[0051] Figure 11 A schematic diagram of the side projection printing module assembly;

[0052] Figure 12 A schematic diagram showing how the position of the rotating print box is determined by collimating laser III;

[0053] Figure 13 Assembly diagram of the volumetric rotation projection printing module;

[0054] Figure 14 A schematic diagram of the stretching process for printing release film;

[0055] Figure 15 This is a detailed view of the side-projection printing box.

[0056] The markings in the diagram are as follows: 1-DMD spatial light modulator, 2-reflector I, 3-405nm LED light source, 4-530nm LED light source I, 5-front collimating lens group, 6-rear condenser lens group, 7-front projection lens group, 8-dichroic mirror, 9-CCD camera, 10-adapter mirror, 11-beam splitter prism, 12-reflecting prism, 13-Z-axis lifting stage bracket, 14-Z-axis lifting stage I, 15-scraper device, 16-automatic large-stroke XY moving platform fixed base I, 17-automatic large-stroke XY moving platform I, 18-printing release film I, 19-Z-axis printing platform, 20-upper projection printing substrate, 21-upper projection printing box, 22-reflector II, 23-lower projection printing substrate, 24-lower projection printing box, 25-rear projection lens group I, 26-rear projection... Mirror assembly II, 27-Lifting turntable, 28-Lifting turntable controller, 29-Rotating printing box, 30-Illumination mirror assembly, 31-530nm LED light source II, 32-Manual Z-axis moving platform, 33-Side projection printing box, 34-Side projection printing box base, 35-Side projection substrate, 36-Side projection substrate lifting bracket, 37-Automatic large stroke XY moving platform II, 38-Automatic large stroke XY moving platform fixed base II, 39-Z-axis lifting platform II, 40-Printing release film II, A1-Collimating laser I, A2-Laser receiving plane, A3-Reflector III, A4-Mechanical fixing frame horizontal plane, A5-Standard plane, A6-Collimating laser II, A7-Collimating laser III, B1-Release film stretching component I, B2-Release film stretching component II, B3-Release film pressing component. Detailed Implementation

[0057] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the invention. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. To avoid obscuring the essence of the invention, well-known methods, processes, flows, elements, and circuits are not described in detail.

[0058] like Figures 1 to 15 As shown, this invention proposes a multifunctional photopolymerization 3D printing device based on DMD, including a DMD spatial light modulator 1, a reflector I 2, a 405nm LED light source 3, a 530nm LED light source I 4, a front collimating lens group 5, a rear condenser lens group 6, a front projection lens group 7, a dichroic mirror 8, a CCD camera 9, an adapter mirror 10, a beam splitter prism 11, a reflecting prism 12, a Z-axis lifting platform bracket 13, a Z-axis lifting platform I 14, a scraper device 15, an automatic large-stroke XY moving platform fixing base I 16, an automatic large-stroke XY moving platform I 17, a printing release film I 18, a Z-axis printing platform 19, and an upper projection... The invention comprises the following components: a printing substrate 20, an upper projection printing box 21, a reflector II 22, a lower projection printing substrate 23, a lower projection printing box 24, a rear projection mirror group I 25, a rear projection mirror group II 26, a lifting turntable 27, a lifting turntable controller 28, a rotating printing box 29, an illumination mirror group 30, a 530nm LED light source II 31, a manual Z-axis moving platform 32, a side projection printing box 33, a side projection printing box base 34, a side projection substrate 35, a side projection substrate lifting bracket 36, an automatic large-stroke XY moving platform II 37, an automatic large-stroke XY moving platform fixed base II 38, a Z-axis lifting platform II 39, and a printing release film II 40. This invention can achieve four types of functions: lower projection 3D printing, upper projection 3D printing, side projection 3D printing, and volumetric rotational projection printing. This invention constructs different printing systems, providing methods for system construction that are simple and highly flexible. It employs a dual-light source focusing method, enabling convenient focusing using the illumination source and real-time observation of the printing interface. Furthermore, it utilizes a combined dual telecentric projection lens group, allowing for the fulfillment of different printing requirements through the combination of various modules. This invention provides a novel method for constructing multi-module 3D printing equipment for fabricating arbitrary three-dimensional continuous complex microstructures.

[0059] The DMD spatial light modulator 1 is fixed on the optical platform by a DMD chip mounting bracket.

[0060] The 405nm LED light source 3, the 530nm LED light source I 4, and their homogenizing devices are fixed on the optical platform by a mechanical mounting bracket. The 405nm LED light source 3 and the 530nm LED light source I 4 are respectively set on both sides of the dichroic mirror 8. The output ends of the homogenizing devices of the 405nm LED light source 3 and the 530nm LED light source I 4 are connected to their respective front collimating mirror groups 5. The collimated light is combined through the dichroic mirror 8 and then enters the DMD spatial light modulator 1 through the rear condenser mirror group 6 and the reflector I 2.

[0061] After determining the focal plane, by adjusting the position of the CCD camera 9, the printed interface can be observed in real time using the 530nm LED light source I4.

[0062] Both the CCD camera 9 and the adapter mirror 10 are fixed on the optical platform by a mechanical mounting bracket, and the CCD camera 9 and the adapter mirror 10 are sequentially arranged on the reflected light path of the beam splitter 11 so that they can receive the reflected light from the rear projection mirror group I 25 or the rear projection mirror group II 26.

[0063] During projection printing, an automatic large-stroke XY moving platform I17 is mounted on the optical platform via an automatic large-stroke XY moving platform fixing base I16. A detachable Z-axis lifting stage I14 is mounted on the automatic large-stroke XY moving platform I17 via a Z-axis lifting stage bracket I13. A manual Z-axis moving platform 32 is mounted directly above the automatic large-stroke XY moving platform I17 and directly below the optical axis of the rear projection lens group I25. A projection printing box 21 is mounted above the manual Z-axis moving platform 32. The vertical position of the upper projection printing box 21 can be adjusted manually via the Z-axis moving platform 32; the Z-axis printing platform 19 is connected to the Z-axis lifting platform I 14, and the projection printing substrate 20 is installed on the Z-axis printing platform 19. By adjusting the position of the Z-axis lifting platform I 14, the Z-axis printing platform 19 and the upper projection printing substrate 20 are placed into the upper projection printing box 21, ensuring that the focal plane is on the upper projection printing substrate 20; wherein the upper projection printing box 21 has a printing release film I 18 and a scraper device 15 on its upper edge.

[0064] During downward projection printing, an automatic large-stroke XY moving platform II38 is installed on the optical platform via an automatic large-stroke XY moving platform fixing base II37. A downward projection printing box 24 and a Z-axis lifting stage II39 are installed on the automatic large-stroke XY moving platform II38, and a downward projection printing substrate 23 is installed on the Z-axis lifting stage II39. The Z-axis lifting stage II39, together with the downward projection printing substrate 23, extends into the downward projection printing box 24, ensuring that the focal plane is on the downward projection printing substrate 23. A reflector II22 is installed on the output light path of the projection lens group II26. The positions of the reflector II22, the Z-axis lifting stage II39, and the downward projection printing substrate 23 are adjusted so that the focal plane is on the downward projection printing substrate 23 and is located at the center of the automatic large-stroke XY moving platform II38.

[0065] During side projection printing, an automatic large-stroke XY moving platform II38 is mounted on the optical platform via an automatic large-stroke XY moving platform fixing base II37. A Z-axis lifting stage II39 is mounted on the automatic large-stroke XY moving platform II38. The side projection substrate 35 is mounted on the Z-axis lifting stage II39 via a side projection substrate lifting bracket 36. The side projection printing box 33 is mounted on the automatic large-stroke XY moving platform II38 via a side projection printing box base 34. A reflecting prism 12 is installed on the output light path of the rear projection lens group I25. The positions of the reflecting prism 12, the Z-axis lifting stage II39, and the side projection substrate 35 are adjusted so that the focal plane is on the side projection substrate 35 and is located at the center of the automatic large-stroke XY moving platform II38. A printing release film II40 is provided on the side edge of the side projection printing box 33.

[0066] The lifting turntable 27 and the lifting turntable controller 28 are fixed to the optical platform by a mechanical bracket, and the rotating printing box 29 is installed below the lifting turntable 27. The illumination lens group 30 and the 530nm LED light source II 31 are placed on one side of the rotating printing box 29 by a mechanical bracket.

[0067] A method for constructing a multifunctional photopolymer 3D printing device based on a DMD is presented. The construction process includes installing a main optical path module, an upper projection printing module, a lower projection printing module, a side projection printing module, and a volume rotation projection printing module. Based on the main optical path module, and in conjunction with these modules, four types of functions—upper projection 3D printing, lower projection 3D printing, side projection 3D printing, and volume rotation projection printing—are achieved.

[0068] The installation process of the main optical path module is described below:

[0069] I. Installation of the main optical path module

[0070] (a) Install a mechanical mounting bracket for fixing the main optical path and a collimating laser IA1 on an optical platform. Install a laser receiving plane A2 on the end face of the collimating laser IA1 on the side where the laser beam is emitted, to receive the reflected light from the collimating laser IA1. The vertical plane of the mechanical mounting bracket is polished to a high-precision smooth surface, serving as the standard surface A5 for assembly. A circular through-hole is opened at the center of the standard surface A5 for mounting and fixing the DMD spatial light modulator 1. Adjust the position of the horizontal plane A4 of the mechanical mounting bracket using a level, ensuring that the laser beam emitted from the collimating laser IA1 can pass through the equal-height circular through-holes fixing each optical element in the mechanical mounting bracket, reach the standard surface A5 at the end of the mechanical mounting bracket, and pass through the center of the circular through-hole in the standard surface A5. Fit the reflecting mirror IIIA3 tightly against the surface of the standard surface A5, ensuring that the normals of the reflecting mirror IIIA3 and the standard surface A5 are aligned. Adjust the relative positions of the collimated laser IA1 and the mechanical mounting bracket so that the laser receiving plane A2 can receive the reflected light spot of the collimated laser IA1, ensuring that the laser can be reflected by the reflector ⅢA3. Adjust the angle of the mechanical mounting bracket using shims so that the reflected light spot on the laser receiving plane A2 coincides with the emitted light spot of the collimated laser IA1. After confirming that the light spots coincide, remove the reflector ⅢA3 and install the DMD spatial light modulator 1 in the original position of the reflector ⅢA3, ensuring that the laser optical axis and the reflecting plane of the DMD spatial light modulator 1 are strictly perpendicular, and that the laser can illuminate the center position of the DMD spatial light modulator 1. Adjust the angle of the DMD spatial light modulator 1 again using shims so that the reflected light spot on the laser receiving plane A2 coincides with the emitted light spot of the collimated laser IA1.

[0071] (II) Install the front projection mirror assembly 7 on the mechanical mounting bracket, ensuring it is in the optical path of the collimated laser IA1 and the DMD spatial light modulator 1. Install the reflector ⅢA3 on the side of the front projection mirror assembly 7 closest to the collimated laser IA1, ensuring the optical axis of the front projection mirror assembly 7 is perpendicular to the surface of the reflector ⅢA3. Adjust the angle of the front projection mirror assembly 7 using shims so that the reflected light spot on the laser receiving plane A2 coincides with the emitted light spot of the collimated laser IA1. After confirming the light spot coincidence, fix the position and angle of the front projection mirror assembly 7 using the mechanical mounting bracket and remove the reflector ⅢA3. Set a beam splitter 11 in the optical path of the emitted light from the front projection mirror assembly 7. Adjust the angle of the beam splitter 11 to ensure that the reflected light spot obtained by the beam splitter 11 on the laser receiving plane A2 coincides with the emitted light spot of the collimated laser IA1. Fix the position and angle of the beam splitter 11 using the mechanical mounting bracket.

[0072] (III) Install collimated laser IIA6 on the optical platform, and install laser receiving plane A2 on the end face of the collimated laser IIA6 on the side of the emitted light to receive the reflected light from the collimated laser IIA6. Install mirror I2 on the mechanical mounting bracket, and adjust the relative position and height of collimated laser IIA6 and mirror I2 so that the emitted light from collimated laser IIA6 can be received and reflected by mirror I2. Adjust the angle of mirror I2 by shims so that the reflected light from collimated laser IIA6 can be incident on the center position of DMD spatial light modulator 1, and the angle between it and the main optical path axis is 24°. The main optical path is the optical path that starts from DMD spatial light modulator 1, passes through front projection mirror group 7, and is emitted through beam splitter prism 11 to rear projection mirror group I25 or rear projection mirror group II26. A dichroic mirror 8 is installed in the optical path of the collimating laser IIA6 and the reflector I2 via a mechanical mounting bracket. The angle of the dichroic mirror 8 is adjusted using shims so that after the light emitted from the collimating laser IIA6 is reflected by the surface of the dichroic mirror 8, the reflected light spot on the laser receiving plane A2 coincides with the emitted light spot of the collimating laser IIA6. A rear condenser lens assembly 6 is installed in the optical path of the dichroic mirror 8 and the reflector I2 via a mechanical mounting bracket. A reflector IIIA3 is installed on the end face of the rear condenser lens assembly 6 near the collimating laser IIA6. The angle of the rear condenser lens assembly 6 is adjusted so that after the light emitted from the collimating laser IIA6 is reflected by the reflector IIIA3, the reflected light spot on the laser receiving plane A2 coincides with the emitted light spot of the collimating laser IIA6.

[0073] (iv) A 405nm LED light source 3 and a 530nm LED light source I 4 are installed on both sides of the dichroic mirror 8. The emission ends of the 405nm LED light source 3 and the 530nm LED light source I 4 are respectively connected to a light homogenizing device. The light homogenizing device is a light homogenizing rod with a rectangular cross-section and an aspect ratio of 1.5. A front collimating lens group 5 is installed between the two light homogenizing devices and the dichroic mirror 8 through a mechanical fixing frame. This allows the emitted light from the 405nm LED light source 3 and the 530nm LED light source I 4 to be homogenized by the light homogenizing device and collimated by the front collimating lens group 5, and then combined through the dichroic mirror 8. The combined collimated light is then directed into the rear condenser lens group 6. With the collimating laser IA1 on, a transition mirror 10 is placed on the reflected light path of the beam splitter 11. A reflecting mirror IIIA3 is installed on the end face of the transition mirror 10 near the beam splitter 11, ensuring that the optical axis of the transition mirror 10 is perpendicular to the surface of the reflecting mirror IIIA3. The angle of the transition mirror 10 is adjusted so that the reflected light spot on the laser receiving plane A2 coincides with the emitted light spot of the collimating laser IA1. After confirming that the light spots coincide, the position and angle of the transition mirror 10 are fixed, the reflecting mirror IIIA3 is removed, and the CCD camera 9 is installed on the optical path after the transition mirror 10 using a mechanical mounting bracket. The front collimating mirror group 5 and the rear condenser mirror group 6 form a double telecentric projection mirror group, thus completing the assembly of the main optical path module.

[0074] The 405nm LED light source 3 and the 530nm LED light source I 4 constitute a dual-band dual-telecentric illumination source. The functions of this dual-band dual-telecentric illumination source are: ① to utilize the 530nm light source for auxiliary imaging, which can be used for focusing and leveling before printing, and tracking during the printing process, without affecting the photocuring process of the printing material; ② to form a uniform rectangular illumination spot that matches the rectangular surface of the DMD spatial light modulator 1, while also having a certain telecentric divergence angle, thus matching the receiving angle of the front projection lens group 7, obtaining a uniformly projected image, and maintaining high energy utilization. The key to the multifunctional photocuring 3D printing device based on DMD designed in this invention, which can combine multiple modules, is the use of separate telecentric projection lenses: the front projection lens group 7 and the rear projection lens group. The function of the front projection lens group 7 is to collimate the light reflected from the DMD spatial light modulator 1, forming parallel light at different angles. The function of the rear projection lens group is to converge the parallel light from different angles of the front projection lens group 7 into an image. The magnification is equal to the focal length of the rear projection lens group divided by the focal length of the front projection lens group 7. The rear projection lens group is either rear projection lens group I 25 or rear projection lens group II 26. Since the light between the front and rear projection lens groups is parallel, and the distance between them can be slightly adjusted, optical operations such as beam splitting and beam combining can be performed on the parallel light portion between the front and rear projection lens groups, thus facilitating the combination of different functional modules. It should be noted that although the rear projection lens group has a certain range of movement relative to the front projection lens group 7, exceeding this range will result in uneven energy distribution, and the receiving aperture angle of the front projection lens group 7 needs to be matched as closely as possible to the divergence angle of the light source emitted by the illumination lens group 30.

[0075] After assembling the main optical path module, installing the projection printing module enables the device to perform projection printing. The installation process of the projection printing module is described below:

[0076] II. Installation of the upper projection printing module

[0077] (a) Install the rear projection mirror assembly I25 on the mechanical mounting bracket, ensuring it is in the optical path of the collimated laser IA1 and the DMD spatial light modulator 1. Install the reflector IIIA3 on the side of the rear projection mirror assembly I25 closest to the collimated laser IA1, ensuring the optical axis of the rear projection mirror assembly I25 is perpendicular to the surface of the reflector IIIA3. Adjust the angle of the rear projection mirror assembly I25 so that the light spot obtained by reflecting the light emitted from the collimated laser IA1 through the center of the reflector IIIA3 coincides with the collimated laser IA1. After confirming the light spot coincidence, fix the position and angle of the rear projection mirror assembly I25 and remove the reflector IIIA3. Fix each optical element in the optical path using the mechanical bracket, ensuring it is perpendicular to the optical platform.

[0078] (II) An automatic large-stroke XY moving platform I17 is set on the optical platform. A detachable Z-axis lifting platform I14 is installed on the automatic large-stroke XY moving platform I17 via a Z-axis lifting platform bracket I13. A manual Z-axis moving platform 32 is installed directly above the automatic large-stroke XY moving platform I17 and directly below the optical axis of the rear projection lens group I25. A projection printing box 21 is installed above the manual Z-axis moving platform 32, so that the vertical position of the upper projection printing box 21 can be adjusted by the manual Z-axis moving platform 32. The Z-axis printing platform 19 is connected to the Z-axis lifting platform I14, and a projection printing substrate 20 is installed on the Z-axis printing platform 19. By adjusting the position of the Z-axis lifting platform I14, the Z-axis printing platform 19 and the upper projection printing substrate 20 are placed into the upper projection printing box 21, ensuring that the focal plane is on the upper projection printing substrate 20.

[0079] In conjunction with the main optical path module, the installation of the lower projection printing module enables the DMD-based multi-functional photopolymerization 3D printing equipment to achieve lower projection printing functionality. The installation process of the projection printing module is described below:

[0080] III. Installation of the Lower Projection Printing Module

[0081] (i) Keeping the collimating laser IA1 on, install a reflector ⅢA3 on the side of the front projection lens group 7 closest to the collimating laser IA1, so that the laser beam is reflected by the reflector ⅢA3 to obtain the reflected light path of the beam splitter 11. Install the collimating laser ⅢA7 on the optical platform, aligning it with the optical axis of the reflected light path of the beam splitter 11 obtained by the collimating laser IA1. After confirming that the optical axes coincide, remove the reflector ⅢA3 on the side of the front projection lens group 7 closest to the collimating laser IA1. A rear projection mirror assembly II 26 is installed in the optical path of the collimating laser IIIA7 and the beam splitter prism 11 via a mechanical mounting bracket. A reflecting mirror IIIA3 is installed on the side of the rear projection mirror assembly II 26 closest to the collimating laser IA1, ensuring that the optical axis of the rear projection mirror assembly II 26 is perpendicular to the surface of the reflecting mirror IIIA3. The angle of the rear projection mirror assembly II 26 is adjusted so that the light spot obtained by reflecting the light emitted from the collimating laser IIIA7 through the center of the reflecting mirror IIIA3 coincides with the light spot emitted from the collimating laser IIIA7. After confirming the light spot coincidence, the position and angle of the rear projection mirror assembly II 26 are fixed, and the reflecting mirror IIIA3 is removed.

[0082] (ii) An automatic large-stroke XY moving platform II37 is installed on the optical platform via an automatic large-stroke XY moving platform fixed base II38. A lower projection printing box 24 and a Z-axis lifting stage II39 are installed on the automatic large-stroke XY moving platform II37. A lower projection printing substrate 23 is installed on the Z-axis lifting stage II39. The Z-axis lifting stage II39, together with the lower projection printing substrate 23, is inserted into the lower projection printing box 24, ensuring that the focal plane is on the lower projection printing substrate 23. The collimating laser IIIA7 is removed, and a reflector II22 is installed on the output optical path of the rear projection lens group II26. The positions of the reflector II22, the Z-axis lifting stage II39, and the lower projection printing substrate 23 are adjusted so that the focal plane is on the lower projection printing substrate 23 and is located at the center of the automatic large-stroke XY moving platform II37.

[0083] In conjunction with the main optical path module, the installation of a side projection printing module enables DMD-based multi-functional photopolymerization 3D printing equipment to achieve side projection printing functionality. The installation process of the side projection printing module is described below:

[0084] IV. Installation of the Side Projection Printing Module

[0085] (a) Install the rear projection mirror assembly I25 on the mechanical mounting bracket, ensuring it is in the optical path of the collimated laser IA1 and the DMD spatial light modulator 1. Install the reflector IIIA3 on the side of the rear projection mirror assembly I25 closest to the collimated laser IA1, ensuring the optical axis of the collimated laser IA1 is perpendicular to the surface of the reflector IIIA3. Adjust the angle of the rear projection mirror assembly I25 so that the light spot obtained by reflecting the light emitted from the collimated laser IA1 through the center of the reflector IIIA3 coincides with the light spot emitted from the collimated laser IA1. After confirming the light spot coincidence, fix the position and angle of the rear projection mirror assembly I25 and remove the reflector IIIA3.

[0086] (ii) An automatic large-stroke XY moving platform II 37 is installed on the optical platform via an automatic large-stroke XY moving platform fixing base II 38. A Z-axis lifting stage II 39 is installed on the automatic large-stroke XY moving platform II 37. The side projection substrate 35 is installed on the Z-axis lifting stage II 39 via a side projection substrate lifting bracket 36. The side projection printing box 33 is installed on the automatic large-stroke XY moving platform II 37 via a side projection printing box base 34. A reflecting prism 12 is installed on the output light path of the rear projection lens group I 25 via a mechanical fixing frame. The positions of the reflecting prism 12, the Z-axis lifting stage II 39, and the side projection substrate 35 are adjusted so that the focal plane is on the side projection substrate 35 and is located at the center of the automatic large-stroke XY moving platform II 37.

[0087] In conjunction with the main optical path module, the volume rotation projection printing module enables DMD-based multifunctional photopolymerization 3D printing equipment to achieve volume rotation projection printing functionality. The installation process of the volume rotation projection printing module is described below:

[0088] V. Installation of the volumetric rotation projection printing module

[0089] (i) Keeping the collimating laser IA1 on, install a reflector ⅢA3 on the side of the front projection lens group 7 closest to the collimating laser IA1, so that the laser output light is reflected by the reflector ⅢA3 to obtain the reflected light path of the beam splitter 11. Install the collimating laser ⅢA7 on the optical platform, aligning it with the optical axis of the reflected light path of the beam splitter 11 obtained by the collimating laser IA1. After confirming that the optical axes coincide, remove the reflector ⅢA3 on the side of the front projection lens group 7 closest to the collimating laser IA1. A rear projection mirror assembly II 26 is installed in the optical path of the collimating laser IIIA7 and the beam splitter prism 11 via a mechanical mounting bracket. A reflecting mirror IIIA3 is installed on the side of the rear projection mirror assembly II 26 closest to the collimating laser IIIA7, ensuring that the optical axis of the rear projection mirror assembly II 26 is perpendicular to the surface of the reflecting mirror IIIA3. The angle of the rear projection mirror assembly II 26 is adjusted so that the light spot obtained by reflecting the light emitted from the collimating laser IIIA7 through the center of the reflecting mirror IIIA3 coincides with the light spot emitted from the collimating laser IIIA7. After confirming that the light spots coincide, the position and angle of the rear projection mirror assembly II 26 are fixed, and the reflecting mirror IIIA3 is removed.

[0090] (II) Install the illumination mirror assembly 30 in the optical path of the collimating laser IIIA7 and the beam splitter prism 11 using a mechanical mounting bracket. Install the reflector IIIA3 on the side of the illumination mirror assembly 30 closest to the collimating laser IIIA7, ensuring that the optical axis of the illumination mirror assembly 30 is perpendicular to the surface of the reflector IIIA3. Adjust the angle of the illumination mirror assembly 30 so that the light spot obtained by reflecting the light emitted from the collimating laser IIIA7 through the center of the reflector IIIA3 coincides with the emitted light spot. After confirming that the light spots coincide, fix the position and angle of the illumination mirror assembly 30, remove the reflector IIIA3, and install the 530nm LED light source II 31 behind the illumination mirror assembly 30. Install the lifting turntable 27 and the lifting turntable controller 28 in the optical path of the illumination mirror assembly 30 and the beam splitter prism 11, and install the rotating printing box 29 below the lifting turntable 27. Adjust the height of the lifting turntable 27 to the focal plane position corresponding to the rear projection mirror assembly II 26 using the lifting turntable controller 28.

[0091] The digital light modulator used in the main optical path module of this invention is a DMD spatial light modulator 1, which is composed of a micromirror array. Different DMD specifications can be selected according to different needs. Each micromirror can switch between +12° on and -12° off according to the input mask.

[0092] The distance between the CCD camera 9 and the adjacent surface of the adapter mirror 10 is 131mm.

[0093] The distance between the front projection lens group 7 and the rear projection lens group is 290mm.

[0094] The distance from the rear projection lens group to the focal plane is 34mm.

[0095] The moving speed of the scraper device 15 is set according to different printing materials, generally 10mm / s.

[0096] The manual z-axis moving platform 32 has a vertical movement range of 10mm.

[0097] The front projection lens group 7, the rear projection lens group I 25, and the rear projection lens group II 26 are all fixed to the optical platform by mechanical mounting brackets, and the zoom ratio of the rear projection lens group II 26 can be changed according to specific printing requirements.

[0098] A release film cover plate is provided above the upper projection printing box 21; the release film cover plate includes a release film stretching component IB1, a release film stretching component IIB2, and a release film pressing component B3; the printed release film I18 is fixed between the release film stretching component IB1 and the release film stretching component IIB2, and the surface of the printed release film I18 is flat and taut under the pressure of the release film pressing component B3, and the lower surface of the printed release film I18 is in contact with the liquid surface.

[0099] While conventional oxygen-permeable membranes offer good oxygen permeability, surface pores can affect the surface precision of the fabricated components. Although PDMS membranes have high surface precision, they are susceptible to deformation due to liquid flow, which can also affect the surface of the fabricated components. Spin-coating a PDMS membrane onto an oxygen-permeable release membrane can provide support for the PDMS and also make the surface of the release membrane smoother, achieving better oxygen permeability and leveling effects.

[0100] Because the lower surface of the release film I18 needs to contact the printing liquid during the printing process, the fluctuations of the printing liquid during printing will affect the flatness of the release film I18. Therefore, release film tensioning components IB1 and IIB2 are needed to stretch the release film I18, lay the release film I18 flat on the release film tensioning component IIB2, and press the release film tensioning component IB1 onto the release film tensioning component IIB2 with screws to make the surface of the release film I18 flat. At the same time, because different release films have different hardness and flexibility, the release film pressing component B3 is needed to further tighten the release film I18 on the framework of the release film tensioning components IB1 and IIB2 to improve the flatness of the release film surface. A similar release film assembly structure can be applied to the top of the upper projection printing box 21 or the side of the side projection printing box 34.

[0101] Taking the above projection printing as an example, the focusing method after adding the release film is as follows: The position of the upper projection printing box 21 is adjusted manually using the Z-axis moving platform 32. The upper projection printing substrate 20 is fixed on the Z-axis printing platform 19, and the Z-axis printing platform 19, along with the upper projection printing substrate 20, is placed into the upper projection printing box 21. Based on the current focal length, the Z-axis printing platform 19 is roughly adjusted to the focal plane position. The printing release film I 18 is installed onto the lower projection printing box 24, i.e., the printing release film I 18 is added to the exposure optical path. The lower projection printing box 24, along with the printing release film I 18, is raised using the Z-axis printing platform 19 to prevent the upper projection printing substrate 20 from accidentally touching the lower surface of the printing release film I 18 during focusing, thus avoiding minor scratches on the printing release film I 18. A focusing pattern is loaded into the DMD spatial light modulator 1, and the Z-axis printing platform 19 is controlled to simultaneously observe the focal plane imaging in the CCD camera 9, adjusting the upper surface of the upper projection printing substrate 20 to the focal plane position. Add printing liquid until it contacts and covers the lower surface of the release film I18. Simultaneously, adjust the upper projection printing substrate 20 to the focal plane position again using the Z-axis printing platform 19. After observing a clear focused image in the CCD camera 9, manually adjust the relative positions of the release film I18 and the upper projection printing substrate 20 using the Z-axis moving platform 32. The distance between the upper surface of the upper projection printing substrate 20 and the lower surface of the release film I18 should be the height at which the release film I18 can produce a "dead zone" (the "dead zone" height varies depending on the release film I18 and the printing liquid, approximately 50µm–100µm). Record the position of the upper projection printing substrate 20 at this point to complete the focusing process.

[0102] The upward projection 3D printing process: The design of the printed element is completed based on CAD, and it is sliced ​​using appropriate slicing software. The sliced ​​files are then input into the DMD spatial light modulator 1. The control program sets the moving speed of the Z-axis printing platform 19 (i.e., the lifting speed of each layer), as well as the exposure time, exposure intensity, and dwell time after each layer. The connection and fixation of each component are checked, and a level is used to ensure that the automatic large-stroke XY moving platform Ⅰ17, the Z-axis printing platform 19, and the upward projection printing substrate 20 are all in a horizontal state. Finally, printing liquid is added, and the focusing process is completed. In the specific printing process, the exposure light source and the DMD spatial light modulator 1 are first controlled to expose the first image at the focal plane position. After completing the corresponding exposure process, the Z-axis printing platform 19 is moved down by one layer thickness and the next image is printed, thus completing the fabrication of the entire element.

[0103] Downward projection 3D printing process: The design of the printed element is completed based on CAD, and it is sliced ​​using appropriate slicing software. The sliced ​​files are then input into the DMD spatial light modulator 1. The moving speed of the Z-axis lifting stage II 39 (i.e., the lifting speed of each layer) is set by the control program, along with the exposure time, exposure intensity, and dwell time after each layer is printed. The connection and fixation of each component are checked, and a level is used to ensure that the downward projection printing box 24, the automatic large-stroke XY moving platform II 37, the automatic large-stroke XY moving platform fixing base II 38, the Z-axis lifting stage II 39, and the downward projection printing substrate 23 are all in a horizontal state. Finally, printing liquid is added, and the focusing process is completed. In the specific printing process, the exposure light source and the DMD spatial light modulator 1 are first controlled to expose the first image at the focal plane position. After completing the corresponding exposure process, the Z-axis lifting stage II 39 is moved upward by one layer thickness and the next image is printed. This cycle is repeated to complete the fabrication of the entire element.

[0104] Side projection 3D printing process: The design of the printed element is completed based on CAD, and it is sliced ​​using appropriate slicing software. The sliced ​​files are then input into the DMD spatial light modulator 1. The moving speed of the Z-axis lifting platform II 39 (i.e., the moving speed of each layer) is set by the control program, along with the exposure time, exposure intensity, and dwell time after each layer is printed. The connection and fixation of each component are checked, and the automatic large-stroke XY moving platform II 37, the automatic large-stroke XY moving platform fixed base II 38, and the Z-axis lifting platform II 39 are all leveled using a level. Finally, printing fluid is added, and the focusing process is completed. In the specific printing process, the exposure light source and DMD spatial light modulator 1 are first controlled to expose the first image at the focal plane position. After completing the corresponding exposure process, the Z-axis lifting platform II 39 is moved backward by one layer thickness to continue printing the next image, thus completing the fabrication of the entire element. Its side view is shown below. Figure 14 As shown.

[0105] Volumetric Rotational Projection Printing: The design of the printed element is completed based on CAD, and it is sliced ​​using appropriate slicing software. The sliced ​​files are then input into the DMD spatial light modulator 1. The control program sets the moving speed of the lifting turntable 27 (i.e., the moving speed of each layer) via the lifting turntable controller 28, and also sets the exposure time, exposure intensity, and dwell time after exposure for each print. The connection and fixation of each component are checked, and a level is used to ensure that the rotating printing box 29 and the lifting turntable 27 are both in a horizontal state. Finally, printing liquid is added, and the focusing process is completed. In the specific printing process, the exposure light source and the DMD spatial light modulator 1 are first controlled to expose the first image at the focal plane position. After completing the corresponding exposure process, the lifting turntable 27 is rotated by the lifting turntable controller 28 at the corresponding angle to continue printing the next image, thus completing the fabrication of the entire element in a cycle.

Claims

1. A method for constructing a multifunctional photopolymerization 3D printing device based on DMD, characterized in that, include: Step 1: Installation of the main optical path module ① Determine the installation position and angle of the DMD spatial light modulator (1); ② Determine the position and angle of the front projection lens group (7) and the beam splitter (11). The beam splitter (11), the front projection lens group (7) and the DMD spatial light modulator (1) are arranged in sequence and the three are on the same optical axis. ③ Determine the position of the reflector I (2) so that the reflected light from the reflector I (2) can be incident on the center of the DMD spatial light modulator (1) and the angle between it and the main optical path optical axis is 24°. The main optical path is formed by the light from the DMD spatial light modulator (1) through the front projection mirror group (7) and the beam splitter (11) to the rear projection mirror group. A dichroic mirror (8) is installed on the incident light path of the reflector I (2). A rear condenser mirror group (6) is installed between the dichroic mirror (8) and the reflector I (2) and the three of them share the same optical axis. ④ Install a 405nm LED light source (3) and a 530nm LED light source I (4) on both sides of the dichroic mirror (8). The output ends of the 405nm LED light source (3) and the 530nm LED light source I (4) are connected to a light homogenizing device. A front collimating lens group (5) is installed between the two light homogenizing devices and the dichroic mirror (8). After the output light of the 405nm LED light source (3) and the 530nm LED light source I (4) is homogenized by the light homogenizing device and collimated by the front collimating lens group (5), it is combined by the dichroic mirror (8). The combined collimated light is then directed into the rear condenser lens group (6), and after passing through the rear condenser lens group (6), it is directed into the DMD spatial light modulator (1) through the reflector I (2). A transducer (10) is set on the reflected light path of the beam splitter (11), and a CCD camera (9) is installed on the light path after the transducer (10). The assembly of the main optical path module is now complete. Step 2: Installation of the four printing function modules Install a projection printing module on top of the main optical path module: The position and angle of the rear projection mirror group I (25) are determined. The rear projection mirror group I (25), the beam splitter (11), the front projection mirror group (7) and the DMD spatial light modulator (1) are sequentially set on the same optical axis. The rear projection mirror group I (25) is set on the transmission light path of the beam splitter (11). An automatic large-stroke XY moving platform I (17) is mounted on an optical platform via an automatic large-stroke XY moving platform fixed base I (16). A detachable Z-axis lifting platform I (14) is mounted on the automatic large-stroke XY moving platform I (17) via a Z-axis lifting platform bracket I (13). A manual Z-axis moving platform (32) is mounted directly above the automatic large-stroke XY moving platform I (17) and directly below the optical axis of the rear projection lens group I (25). A [unclear text - possibly a device or component] is mounted above the manual Z-axis moving platform (32). Projection printing box (21), so that the vertical position of the upper projection printing box (21) can be adjusted by manually moving the Z-axis platform (32); connect the Z-axis printing platform (19) to the Z-axis lifting platform I (14), and install the projection printing substrate (20) on the Z-axis printing platform (19). By adjusting the position of the Z-axis lifting platform I (14), the Z-axis printing platform (19) and the upper projection printing substrate (20) are placed into the upper projection printing box (21) and the focal plane is on the upper projection printing substrate (20); Install the projection printing module on top of the main optical path module: The position and angle of the rear projection lens group II (26) are fixed to ensure that the CCD camera (9), the adapter (10), the beam splitter (11) and the rear projection lens group II (26) are on the same optical axis, and the rear projection lens group II (26) is set on the reflected light path of the beam splitter (11); the automatic large-stroke XY moving platform II (38) is installed on the optical platform via the automatic large-stroke XY moving platform fixed base II (37), and the projection printing box (24) and the Z-axis lifting stage II (39) are installed on the automatic large-stroke XY moving platform II (38) respectively, and the Z-axis is... The lower projection printing substrate (23) is installed on the lifting platform II (39), and the Z-axis lifting platform II (39) together with the lower projection printing substrate (23) is inserted into the lower projection printing box (24), ensuring that the focal plane is on the lower projection printing substrate (23); the reflector II (22) is installed on the outgoing light path of the projection lens group II (26), and the positions of the reflector II (22), the Z-axis lifting platform II (39) and the lower projection printing substrate (23) are adjusted so that the focal plane is on the lower projection printing substrate (23) and is in the center position of the automatic large stroke XY moving platform II (38); Install a side projection printing module on top of the main optical path module: The position and angle of the rear projection lens group I (25) are kept the same as those of the rear projection lens group I (25) in the upper projection printing module. An automatic large-stroke XY moving platform II (38) is installed on the optical platform via an automatic large-stroke XY moving platform fixed base II (37). A Z-axis lifting stage II (39) is installed on the automatic large-stroke XY moving platform II (38). The side projection substrate (35) is installed on the Z-axis lifting stage II (39) via a side projection substrate lifting bracket (36). The side projection printing box (33) is installed on the automatic large-stroke XY moving platform II (38) via a side projection printing box base (34). A reflecting prism (12) is installed on the outgoing light path of the rear projection lens group I (25). The positions of the reflecting prism (12), the Z-axis lifting stage II (39), and the side projection substrate (35) are adjusted so that the focal plane is on the side projection substrate (35) and is located at the center of the automatic large-stroke XY moving platform II (38). Install a volume rotation projection printing module on top of the main optical path module: The position and angle of the rear projection lens group II (26) are kept the same as those of the rear projection lens group II (26) in the lower projection printing module. The position and angle of the illumination lens group (30) are fixed in the outgoing light path of the rear projection lens group II (26), and a 530nm LED light source II (31) is installed behind the illumination lens group (30). A lifting turntable (27) and a lifting turntable controller (28) are installed in the light path of the illumination lens group (30) and the beam splitter (11). The rotating printing box (29) is installed below the lifting turntable (27). The lifting turntable (27) is equipped with a lifting turntable controller (28), and the height of the lifting turntable (27) is adjusted to the focal plane exposure position corresponding to the rear projection lens group II (26) by the lifting turntable controller (28).

2. The method for constructing a multifunctional photopolymerization 3D printing device based on DMD according to claim 1, characterized in that, Step 1, ① includes: A mechanical mounting bracket for fixing the main optical path and a collimated laser I (A1) are installed on an optical platform. A laser receiving plane (A2) is installed on the end face of the collimated laser I (A1) on the side of the emitted light to receive the reflected light from the collimated laser I (A1). The vertical plane of the mechanical mounting bracket is polished and serves as the standard surface (A5) for assembly. A circular through hole is opened in the center of the standard surface (A5) for installing and fixing the DMD spatial light modulator (1). The position of the horizontal plane of the mechanical mounting bracket is adjusted by a level so that the laser light emitted from the collimated laser I (A1) can reach the standard surface (A5) at the end of the mechanical mounting bracket and pass through the center of the circular through hole in the standard surface (A5). The reflector III (A3) is tightly attached to the surface of the standard surface (A5) so that the normals of the reflector III (A3) and the standard surface (A5) are aligned. The collimated laser I (A1) is then adjusted. The relative position of the mechanical mounting bracket is adjusted so that the laser receiving plane (A2) can receive the reflected light spot of the collimated laser I (A1), so that the laser can be reflected by the mirror III (A3). The angle of the mechanical mounting bracket is adjusted by the shims so that the reflected light spot on the laser receiving plane (A2) coincides with the emitted light spot of the collimated laser I (A1). After confirming that the light spots coincide, the mirror III (A3) is removed and the DMD spatial light modulator (1) is installed in the original position of the mirror III (A3). The laser optical axis and the reflection plane of the DMD spatial light modulator (1) are completely perpendicular, and the laser can illuminate the center position of the DMD spatial light modulator (1). The angle of the DMD spatial light modulator (1) is adjusted again by the shims so that the reflected light spot on the laser receiving plane (A2) coincides with the emitted light spot of the collimated laser I (A1).

3. The method for constructing a multifunctional photopolymerization 3D printing device based on DMD according to claim 2, characterized in that, Step 1, ② includes: Install the front projection mirror assembly (7) on the mechanical mounting bracket, ensuring that it is in the optical path of the collimated laser I (A1) and the DMD spatial light modulator (1). Install the reflector III (A3) on the side of the front projection mirror assembly (7) closest to the collimated laser I (A1), ensuring that the optical axis of the front projection mirror assembly (7) is perpendicular to the surface of the reflector III (A3). Adjust the angle of the front projection mirror assembly (7) so that the reflected light spot on the laser receiving plane (A2) coincides with the emitted light spot of the collimated laser I (A1). After confirming that the light spots coincide, fix the position and angle of the front projection mirror group (7) with a mechanical fixing frame and remove the reflector III (A3); set a beam splitter (11) in the light path of the light emitted from the front projection mirror group (7), adjust the angle of the beam splitter (11) to ensure that the reflected light spot obtained by the beam splitter (11) on the laser receiving plane (A2) coincides with the light emitted from the collimated laser I (A1), and fix the position and angle of the beam splitter (11) with a mechanical fixing frame.

4. The method for constructing a multifunctional photopolymerization 3D printing device based on DMD according to claim 3, characterized in that, Step 1, ③ includes: A collimated laser II (A6) is installed on an optical platform, and a laser receiving plane (A2) is installed on the end face of the collimated laser II (A6) on the side of the emitted light to receive the reflected light from the collimated laser II (A6). A reflector I (2) is installed on a mechanical mounting frame. The relative position and height of the collimated laser II (A6) and the reflector I (2) are adjusted so that the emitted light from the collimated laser II (A6) can be received and reflected by the reflector I (2). By adjusting the angle of the reflector I (2), the reflected light from the collimated laser II (A6) can be incident on the center position of the DMD spatial light modulator (1), and the angle between it and the main optical path axis is 24°. The optical paths of the collimated laser II (A6) and the reflector I (2) are connected by a reflector I (2). A dichroic mirror (8) is installed via a mechanical mounting bracket. The angle of the dichroic mirror (8) is adjusted by shims so that the light emitted from the collimated laser II (A6) is reflected by the surface of the dichroic mirror (8), and the reflected spot on the laser receiving plane (A2) coincides with the light emitted from the collimated laser II (A6). A rear condenser assembly (6) is installed on the optical path of the dichroic mirror (8) and the reflector I (2) via a mechanical mounting bracket. A reflector III (A3) is installed on the end face of the rear condenser assembly (6) near the collimated laser II (A6). The angle of the rear condenser assembly (6) is adjusted so that the light beam emitted from the collimated laser II (A6) is reflected by the reflector III (A3), and the reflected spot on the laser receiving plane (A2) coincides with the original light emitted.

5. The method for constructing a multifunctional photopolymerization 3D printing device based on DMD according to claim 4, characterized in that, In step 1, ④, the specific operation process of setting a transition mirror (10) on the reflected light path of the beam splitter (11) and installing a CCD camera (9) on the light path after the transition mirror (10) is as follows: Keep the collimating laser I (A1) on, set up a transition mirror (10) in the optical path of the beam splitter (11) and the output light of the collimating laser I (A1), install a reflector III (A3) on the end face of the transition mirror (10) near the beam splitter (11), ensure that the optical axis of the transition mirror (10) is perpendicular to the surface of the reflector III (A3), adjust the angle of the transition mirror (10) so that the reflected light spot on the laser receiving plane (A2) coincides with the output light spot of the collimating laser I (A1); after confirming that the light spots coincide, fix the position and angle of the transition mirror (10), remove the reflector III (A3), and install a CCD camera (9) in the optical path after the transition mirror (10).

6. The method for constructing a multifunctional photopolymerization 3D printing device based on DMD according to claim 5, characterized in that, During the installation of the upper projection printing module and the side projection printing module, the process of determining the position and angle of the rear projection mirror group I is as follows: Install the rear projection mirror assembly I (25) on the mechanical mounting bracket, ensuring that it is in the optical path of the collimated laser I (A1) and the DMD spatial light modulator (1); install the reflector III (A3) on the side of the rear projection mirror assembly I (25) close to the collimated laser I (A1), ensuring that the optical axis of the rear projection mirror assembly I (25) is perpendicular to the surface of the reflector III (A3), adjust the angle of the rear projection mirror assembly I (25) so that the light spot obtained by the reflection of the collimated laser I (A1) through the center of the reflector III (A3) coincides with the light emitted by the collimated laser I (A1); after confirming that the light spots coincide, fix the position and angle of the rear projection mirror assembly I (25) and remove the reflector III (A3).

7. The method for constructing a multifunctional photopolymerization 3D printing device based on DMD according to claim 6, characterized in that, The specific steps involved in installing the projection printing module on top of the main optical path module include: Keep collimating laser I (A1) on. Install mirror III (A3) on the side of the front projection lens group (7) closest to collimating laser I (A1), so that the laser output light is reflected by mirror III (A3) to obtain the reflected light path of beam splitter (11). Install collimating laser III (A7) on the optical platform, so that the optical axis of its output light is consistent with the optical axis of the reflected light path of beam splitter (11) obtained by collimating laser I (A1). After confirming that the two optical axes coincide, remove mirror III (A3) on the side of the front projection lens group (7) closest to collimating laser I (A1). In the optical path of the optical prism (11), the rear projection mirror group II (26) is installed through a mechanical fixing bracket. The reflector III (A3) is installed on the side of the rear projection mirror group II (26) close to the collimating laser I (A1), and the optical axis of the rear projection mirror group II (26) is perpendicular to the surface of the reflector III (A3). The angle of the rear projection mirror group II (26) is adjusted so that the light spot obtained by the collimating laser III (A7) after being reflected by the center of the reflector III (A3) coincides with the light spot of the collimating laser III (A7). After confirming that the light spots coincide, the position and angle of the rear projection mirror group II (26) are fixed, and the reflector III (A3) is removed. An automatic large-stroke XY moving platform II (38) is installed on an optical platform via an automatic large-stroke XY moving platform fixed base II (37). A lower projection printing box (24) and a Z-axis lifting stage II (39) are installed on the automatic large-stroke XY moving platform II (38). A lower projection printing substrate (23) is installed on the Z-axis lifting stage II (39). The Z-axis lifting stage II (39) and the lower projection printing substrate (23) are inserted into the lower projection printing box (24) and the focal plane is ensured to be on the lower projection printing substrate (23). The collimating laser III (A7) is removed, and a reflector II (22) is installed on the output light path of the rear projection lens group II (26). The positions of the reflector II (22), the Z-axis lifting stage II (39), and the lower projection printing substrate (23) are adjusted so that the focal plane is on the lower projection printing substrate (23) and is located at the center of the automatic large-stroke XY moving platform II (38).

8. The method for constructing a multifunctional photopolymerization 3D printing device based on DMD according to claim 7, characterized in that, In the operation of installing the volumetric rotation projection printing module based on the main optical path module, the specific operation process of fixing the position and angle of the illumination lens group (30) on the output optical path of the rear projection lens group II (26) is as follows: An illumination mirror assembly (30) is installed in the optical path of the collimating laser III (A7) and the beam splitter (11) using a mechanical mounting bracket. A reflector III (A3) is installed on the side of the illumination mirror assembly (30) closest to the collimating laser III (A7), ensuring that the optical axis of the illumination mirror assembly (30) is perpendicular to the surface of the reflector III (A3). The angle of the illumination mirror assembly (30) is adjusted so that the light spot obtained by the reflection of the collimating laser III (A7) through the center of the reflector III (A3) coincides with the light spot. After confirming that the light spots coincide, the position and angle of the illumination mirror assembly (30) are fixed, and the reflector III (A3) is removed.

9. A DMD-based multifunctional photopolymer 3D printing device, which is constructed using the construction method of the DMD-based multifunctional photopolymer 3D printing device according to any one of claims 1-8.

Images