Dynamic focus area printing optical path system based on optical path compensation and projection system

Abstract

The present invention discloses a dynamic focus surface area printing optical path system based on optical path compensation and projection system, including a light source system, a mapping system, a projection system, an optical path compensation system and a scanning system. The optical path system optimizes the design of the system optical path, combines the light source system, the mapping system, the projection system, the optical path compensation system and the scanning system, and constructs a system optical path that improves the imaging accuracy, power uniformity and imaging consistency of different positions of the working surface. The present invention relates to the field of printing optical path technology. The dynamic focus surface area printing optical path system based on optical path compensation and projection system solves the industry pain points of distortion and poor energy uniformity in existing surface printing equipment through the design of the optical path system, especially the mapping system and the projection system, thereby improving printing efficiency and quality.

Description

Technical Field

[0001] The invention relates to the technical field of printing optical paths, in particular to a dynamic focusing surface area printing optical path system based on optical path compensation and a projection system. Background Art

[0002] At present, in the laser 3D printing industry, high-power lasers are generally used in conjunction with galvanometers for point-by-point scanning, but this method has the problems of slow forming speed and low work efficiency. In order to effectively improve the forming efficiency and size of the equipment, most of them adopt the method of increasing the number of lasers. But on the one hand, the increase in the number of lasers means an increase in the number of splicing areas, and the splicing quality is related to many factors such as the temperature drift of the galvanometer after long-term operation and the stability of the mechanical structure. The more splicing areas there are, the more difficult it is to ensure the splicing quality, and the higher the risk of product quality problems. On the other hand, the introduction of multiple lasers not only increases the equipment cost, but the number of galvanometers will also increase with the increase in the number of lasers. Accurate printing requires precise calibration and special thermal management, which will greatly increase the complexity of the system and is not conducive to actual production applications.

[0003] Laser surface area printing uses laser beam shaping and pattern modulation technology. According to the pattern characteristics of the subdivided model of the printed part, the high-power laser spot is modulated into a surface area pattern with specific patterns and energy distribution characteristics, and then projected onto the powder bed in sequence to achieve overall melting printing of the powder in the surface area. The scanning printing unit is upgraded from "point" to "surface", which is a disruptive technology compared to traditional laser 3D printing and an effective way to solve the problems of low forming efficiency and high cost. However, the surface area printing optical path design currently used for laser additive manufacturing has defects in the optical design module, resulting in serious distortion of the spot image on the printed surface, uneven power, and inconsistent images at different positions, which affects the overall printing efficiency and quality.

[0004] To solve the above problems, the present invention provides a surface area printing optical path for laser additive manufacturing. By optimizing the design of the system optical path, combining the light source system, mapping system, projection system, optical path compensation system (dynamic focusing) and scanning system, a system optical path is constructed to improve the imaging accuracy, power uniformity and imaging consistency of the working surface, thereby improving printing efficiency and quality. Summary of the invention

[0005] 1. Technical issues to be solved

[0006] In view of the shortcomings of the prior art, the present invention provides a dynamic focal surface area printing optical path system based on optical path compensation and projection system, which is used to solve the problems of distortion, poor power uniformity and poor image consistency at different positions on the working surface existing in the prior art, thereby improving printing efficiency and quality.

[0007] (II) Technical solution

[0008] To achieve the above objectives, the present invention is implemented through the following technical solutions: a dynamic focus surface area printing optical path system based on an optical path compensation and projection system, including a light source system, a mapping system, a projection system, an optical path compensation system and a scanning system. The optical path system optimizes the design of the system optical path, combines the light source system, the mapping system, the projection system, the optical path compensation system and the scanning system, and constructs a system optical path that improves the imaging accuracy, power uniformity and imaging consistency of different positions of the working surface;

[0009] The light source system is composed of a 1064nm polarization-maintaining laser and a beam shaping module, and the light source system is used to provide a collimated and homogenized linearly polarized printing light source;

[0010] The mapping system is composed of a computer device, a blue light projector, a semi-transparent and semi-reflective mirror, a spatial light modulator OALV, a polarization beam splitter PBS and a beam recycling system, and the mapping system is used to couple pattern information to the printing light;

[0011] The optical path design of the projection system adopts a deformed double Gaussian structure design, the purpose of which is to conjugate the printed image generated by the mapping system to the work surface clearly and without distortion, while controlling the magnification, that is, the image size, to ensure that the power density meets the printing requirements;

[0012] The optical path compensation system is composed of multiple reflectors, and its purpose is to solve the problem of defocusing of the projection system caused by changes in working distance due to printing at different positions on the format, which in turn leads to poor image consistency at different positions on the working surface;

[0013] The scanning system is composed of two reflective mirrors with orthogonal reflective surfaces. Its purpose is to move the two reflective mirrors through a precision linear motion module to achieve XY surface scanning of the optical path system, while the formed part moves in the Z axis direction to achieve three-dimensional scanning.

[0014] Preferably, the 1064nm polarization-maintaining laser is used to generate a linearly polarized light source for use as a printing light source.

[0015] Preferably, the beam shaping module is used to collimate and homogenize the printing light source, and its focal plane is at the spatial light modulator OALV of the imaging system.

[0016] Preferably, the computer device and the blue light projector are used to generate target pattern indication light, wherein the blue light projector is co-focal with a beam shaping module in the light source system.

[0017] Preferably, the semi-transparent and semi-reflective mirror couples the target pattern indicator light generated by the blue light projector to the system optical path, and the spatial light modulator OALV is the cofocal plane of the beam shaping module and the blue light projector module, the spot size of the printing light L1 shaped by the beam shaping module is D1, and the spot size of the indicator light L2 generated by the blue light projector is D2, wherein the liquid crystal crystal is deflected when the light field of the indicator light L2 passes through the OALV, causing the polarization state of the printing light L1 and the indicator light L2 to be deflected in the overlapping area when passing through the OALV, and the overlapping area and the non-overlapping area of ​​the printing light L1 and the indicator light L2 after passing through the OALV have a phase difference of π / 2, and the polarization states are perpendicular to each other; after the printing light L1 and the indicator light L2 pass through the PBS, the non-overlapping area is reflected by the polarization beam splitter PBS to the optical path recovery system for conversion and absorption, and the overlapping area optical path carries the printing information to the working surface.

[0018] Preferably, the spot size D1 of the printing light L1 is greater than the spot size D2 of the indication light L2.

[0019] Preferably, the front focal plane of the projection system is confocal with the beam shaping module and the blue light projector, the image space of the beam shaping module and the blue light projector is the object space of the projection optical path system, and the image aperture angle θ of the beam shaping module is 1 That is, the object aperture angle θ of the projection light path 2， where θ 2 >θ 1 , to ensure the coupling of the two optical paths.

[0020] Preferably, the working principle of the optical path compensation system is: by moving the optical path compensation system in the reverse direction to compensate for the change in the working distance of the projection system caused by imaging at different positions of the working surface, it is ensured that the working distance of the projection system is the optimal working distance when imaging at different positions of the working surface.

[0021] (III) Beneficial effects

[0022] The present invention provides a dynamic focus area printing optical path system based on optical path compensation and projection system. Compared with the prior art, it has the following beneficial effects:

[0023] (1) The dynamic focusing surface area printing optical path system based on optical path compensation and projection system solves the industry pain points of distortion and poor energy uniformity in existing surface printing equipment through the design of the optical path system, especially the mapping system and projection system, thereby improving printing efficiency and quality.

[0024] (2) The dynamic focus surface area printing optical path system based on the optical path compensation and projection system solves the problem of poor image consistency at different positions on the working surface of the existing surface printing equipment through the design of the optical path system, especially the projection system and the optical path compensation system, and ensures the surface quality and structural performance of large-format printed workpieces.

[0025] (3) The dynamic focusing surface area printing optical path system based on optical path compensation and projection system is aimed at the fact that most of the current laser additive manufacturing equipment is based on the laser selective melting forming process, which realizes the forming from point to line, line to surface, and surface to body by melting and stacking powder layer by layer, and its forming efficiency and forming size are greatly limited. The present invention uses surface area printing technology to achieve the melting forming of the surface area with one pulse, wherein the fine control of laser power and exposure time is achieved through the coordination of the mapping system and the projection system, so that the surface area printing can better control the melting process, further realize high-resolution printing, manufacture gradient materials, perform support-free printing, and eliminate splashes. In addition, compared with traditional single-laser, dual-laser, four-laser or even more laser additive manufacturing equipment, the surface area printing system has greatly reduced system complexity and greatly improved the forming and construction speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the optical path principle of the present invention;

[0027] Figure 2 This is a projection optical path system diagram of the present invention;

[0028] Figure 3 This is a simulation diagram of the uniformity of the light field on the working surface without a projection lens of the present invention;

[0029] Figure 4 This is a simulation diagram of the uniformity of the light field of the working surface of the projection lens of the present invention;

[0030] Figure 5 This is a simulation diagram of the distortion phenomenon of the working surface without a projection lens of the present invention;

[0031] Figure 6 This is a simulation diagram of the distortion phenomenon of the working surface of the projection lens of the present invention;

[0032] Figure 7 It is a simulation diagram of the light field energy distribution at different positions of the working surface of the present invention, which only contains the projection system and no optical path compensation system when imaging at an ideal working distance of -100mm;

[0033] Figure 8 It is a simulation diagram of the light field energy distribution at different positions on the working surface of the present invention, which only contains the projection system and no optical path compensation system when imaging at an ideal working distance. DETAILED DESCRIPTION

[0034] 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.

[0035] See also Figure 1-8 The embodiment of the present invention provides two technical solutions: a dynamic focus area printing optical path system based on optical path compensation and projection system, specifically including the following embodiments:

[0036] Embodiment 1: A dynamic focus surface area printing optical path system based on an optical path compensation and projection system, including a light source system, a mapping system, a projection system, an optical path compensation system and a scanning system. The optical path system optimizes the design of the system optical path, combines the light source system, the mapping system, the projection system, the optical path compensation system and the scanning system, and constructs a system optical path that improves the imaging accuracy, power uniformity and imaging consistency of different positions of the working surface;

[0037] The light source system is composed of a 1064nm polarization-maintaining laser and a beam shaping module, and the light source system is used to provide a collimated and homogenized linearly polarized printing light source;

[0038] The mapping system is composed of a computer device, a blue light projector, a semi-transparent and semi-reflective mirror, a spatial light modulator OALV, a polarization beam splitter PBS and a beam recycling system, and the mapping system is used to couple pattern information to the printing light;

[0039] The optical path design of the projection system adopts a deformed double Gaussian structure design, the purpose of which is to conjugate the printed image generated by the mapping system to the work surface clearly and without distortion (<3%), while controlling the magnification, that is, the image size, to ensure that the power density meets the printing requirements;

[0040] The optical path compensation system is composed of multiple reflectors, and its purpose is to solve the problem of defocusing of the projection system caused by changes in working distance due to printing at different positions on the format, which in turn leads to poor image consistency at different positions on the working surface;

[0041] The scanning system is composed of two reflective mirrors with orthogonal reflective surfaces. Its purpose is to move the two reflective mirrors through a precision linear motion module to achieve XY surface scanning of the optical path system, while the formed part moves in the Z axis direction to achieve three-dimensional scanning.

[0042] In the embodiment of the present invention, a 1064nm polarization-maintaining laser is used to generate a linearly polarized light source for use as a printing light source, and a beam shaping module is used to collimate and homogenize the printing light source, with its focal plane (i.e., homogenizing plane) being at the spatial light modulator OALV of the imaging system.

[0043] In the embodiment of the present invention, the computer device and the blue light projector are used to generate a target pattern indicator light, wherein the blue light projector is confocal with the beam shaping module in the light source system (the focal plane position is at OALV), the semi-transparent and semi-reflective mirror couples the target pattern indicator light generated by the blue light projector to the system optical path, and the spatial light modulator OALV is the confocal plane of the beam shaping module and the blue light projector module, the print light L1 shaped by the beam shaping module has a spot size D1, and the indicator light L2 generated by the blue light projector has a spot size D2, wherein the indicator light L2 light field The liquid crystal crystal is deflected when passing through OALV, causing the polarization state of the printing light L1 (linear polarization) to be deflected in the overlapping area with the indicator light L2 when passing through OALV. After passing through OALV, the printing light L1 and the indicator light L2 have a phase difference of π / 2 in the overlapping area and the non-overlapping area, and the polarization states are perpendicular to each other; after passing through PBS, the non-overlapping area of ​​the printing light L1 and the indicator light L2 is reflected by the polarization beam splitter PBS to the optical path recovery system for conversion and absorption, and the optical path of the overlapping area carries the printing information to the working surface, and the spot size D1 of the printing light L1 is greater than the spot size D2 of the indicator light L2.

[0044] Embodiment 2: The technical solution of the embodiment of the present invention is different from that of embodiment 1 in that the front focal plane of the projection system is confocal with the beam shaping module and the blue light projector (i.e., at OLAV), the image space of the beam shaping module and the blue light projector is the object space of the projection optical path system, and the image aperture angle θ of the beam shaping module is 1 That is, the object aperture angle θ of the projection light path 2， where θ 2 >θ 1 , to ensure the coupling of the two optical paths.

[0045] In the embodiment of the present invention, the working principle of the optical path compensation system is: by moving the optical path compensation system in the reverse direction to compensate for the change in the working distance of the projection system caused by imaging at different positions of the working surface, it is ensured that when imaging at different positions of the working surface, the working distance of the projection system is the optimal working distance.

[0046] In summary, the present invention solves the industry pain points of distortion and poor energy uniformity in existing surface printing equipment through the design of the optical path system, especially the mapping system and the projection system, thereby improving the printing efficiency and quality. The optical path system design, especially the projection system and the optical path compensation system, solves the problem of poor image consistency at different positions on the working surface of the existing surface printing equipment, and ensures the surface quality and organizational performance of large-format printed workpieces. Most of the current laser additive manufacturing equipment is based on the laser selective melting forming process, and the powder is melted and superimposed layer by layer to achieve the forming from point to line, line to surface, and surface to body, and its forming efficiency and forming size are greatly limited. The present invention uses the surface area printing technology to enable one pulse to achieve the melting forming of the surface area, wherein the fine control of the laser power and exposure time is achieved through the cooperation of the mapping system and the projection system, so that the surface area printing can better control the melting process, further realize high-resolution printing, manufacture gradient materials, perform unsupported printing, and eliminate splashes. In addition, compared with traditional single-laser, dual-laser, four-laser or even more laser additive manufacturing equipment, the system complexity of surface area printing is greatly reduced, and the forming construction speed is greatly improved.

[0047] Meanwhile, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

[0048] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0049] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A dynamic focus area printing optical path system based on optical path compensation and projection system, characterized in that: The optical path system includes a light source system, a mapping system, a projection system, an optical path compensation system and a scanning system. The optical path system optimizes the design of the system optical path and combines the light source system, the mapping system, the projection system, the optical path compensation system and the scanning system to construct a system optical path that improves the imaging accuracy, power uniformity and imaging consistency of different positions of the working surface; The light source system is composed of a 1064nm polarization-maintaining laser and a beam shaping module, and the light source system is used to provide a collimated and homogenized linearly polarized printing light source; The mapping system is composed of a computer device, a blue light projector, a semi-transparent and semi-reflective mirror, a spatial light modulator OALV, a polarization beam splitter PBS and a beam recycling system, and the mapping system is used to couple pattern information to the printing light; The optical path design of the projection system adopts a deformed double Gaussian structure design, the purpose of which is to conjugate the printed image generated by the mapping system to the work surface clearly and without distortion, while controlling the magnification, that is, the image size, to ensure that the power density meets the printing requirements; The optical path compensation system is composed of multiple reflectors, and its purpose is to solve the problem of defocusing of the projection system caused by changes in working distance due to printing at different positions on the format, which in turn leads to poor image consistency at different positions on the working surface; The scanning system is composed of two reflective mirrors with orthogonal reflective surfaces. Its purpose is to move the two reflective mirrors through a precision linear motion module to achieve XY surface scanning of the optical path system, while the formed part moves in the Z axis direction to achieve three-dimensional scanning.

2. The dynamic focal plane area printing optical path system based on optical path compensation and projection system according to claim 1, characterized in that: The 1064nm polarization-maintaining laser is used to generate a linearly polarized light source for use as a printing light source.

3. The dynamic focal plane area printing optical path system based on optical path compensation and projection system according to claim 1, characterized in that: The beam shaping module is used to collimate and homogenize the printing light source, and its focal plane is at the spatial light modulator OALV of the imaging system.

4. The dynamic focal plane area printing optical path system based on optical path compensation and projection system according to claim 1, characterized in that: The computer device and the blue light projector are used to generate target pattern indication light, wherein the blue light projector is co-focused with a beam shaping module in the light source system.

5. The dynamic focal plane area printing optical path system based on optical path compensation and projection system according to claim 1, characterized in that: The semi-transparent and semi-reflective mirror couples the target pattern indicator light generated by the blue light projector to the system optical path, and the spatial light modulator OALV is the cofocal plane of the beam shaping module and the blue light projector module. The spot size of the printing light L1 shaped by the beam shaping module is D1, and the spot size of the indicator light L2 generated by the blue light projector is D2. When the light field of the indicator light L2 passes through the OALV, the liquid crystal crystal is deflected, resulting in the polarization state of the printing light L1 and the indicator light L2 overlapping area being deflected when passing through the OALV. After the printing light L1 and the indicator light L2 pass through the OALV, the overlapping area and the non-overlapping area generate a phase difference of π / 2, and the polarization states are perpendicular to each other; after the printing light L1 and the indicator light L2 pass through the PBS, the non-overlapping area is reflected by the polarization beam splitter PBS to the optical path recovery system for conversion and absorption, and the overlapping area optical path carries the printing information to the working surface.

6. The dynamic focal plane area printing optical path system based on optical path compensation and projection system according to claim 5, characterized in that: The spot size D1 of the printing light L1 is greater than the spot size D2 of the indication light L2.

7. The dynamic focal plane area printing optical path system based on optical path compensation and projection system according to claim 1, characterized in that: The front focal plane of the projection system is confocal with the beam shaping module and the blue light projector. The image space of the beam shaping module and the blue light projector is the object space of the projection optical path system. The image-side aperture angle θ1 of the beam shaping module is the object-side aperture angle θ of the projection optical path. 2， Among them, θ2>θ1, so as to ensure the coupling of the two optical paths.

8. The dynamic focal plane area printing optical path system based on optical path compensation and projection system according to claim 1, characterized in that: The working principle of the optical path compensation system is: by moving the optical path compensation system in reverse to compensate for the change in the working distance of the projection system caused by imaging at different positions of the working surface, it is ensured that the working distance of the projection system is the optimal working distance when imaging at different positions of the working surface.

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