High-definition lens applied to 3D printing

Abstract

The invention provides a high-definition lens module applied to 3D printing, and relates to the technical field of optical imaging. The high-definition lens comprises a first lens group, a second lens group, a diaphragm, a third lens group, a fourth lens group and an imaging chip group which are sequentially arranged from an object space side to an image space side along an optical axis, according to the invention, ultraviolet light is emitted based on the MicroLED high-resolution chip, and is projected and photocured through the imaging lens, so that the problems of high DLP cost, complex structure rear group, small imaging lens aperture and low lens resolution in the DLP type 3D printer technology in the prior art are solved.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a high-definition lens for 3D printing. Background Technology

[0002] 3D printing is a type of rapid prototyping technology that uses digital model files as a basis and employs bondable materials such as powdered metal or plastic to construct objects layer by layer. Currently, 3D printing technology is widely used in fields such as industrial design, architecture, aerospace, and education.

[0003] DLP (Digital Light Processing) 3D printers mainly utilize DLP projection to focus ultraviolet light from the entire surface onto the surface of the 3D printing material, and are characterized by high printing speed.

[0004] Currently, 3D printing still has many shortcomings in the market: 1. DLP chips have a monopoly and are expensive; 2. The DLP-3D printing module, excluding the imaging projection module, has a complex structure (including the illumination group). 3. Imaging projection lenses have low resolution (maximum 1080p), high distortion (0.5%), and small aperture (F# between 1.5 and 2). Therefore, with the development of materials technology and hardware equipment technology, the demand for miniaturization, high resolution, and low cost in 3D printing technology will become the trend in its development. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, the purpose of this invention is to provide a high-definition lens module for 3D printing. This invention is based on the ultraviolet light emitted by a MicroLED high-resolution chip, which is projected through an imaging lens for light curing to solve the problems of high cost and complex structure of DLP 3D printers, as well as small aperture (generally between 1.5 and 3) and low resolution of imaging lenses in existing DLP 3D printer technologies.

[0006] To achieve the above objectives, the present invention provides the following solution: A high-definition lens for 3D printing, comprising: The first mirror group, the second mirror group, the aperture, the third mirror group, the fourth mirror group, and the imaging chip group are arranged sequentially along the optical axis from the object side to the image side. The imaging chip group is used to emit light to obtain preliminary light output; the fourth lens group is used to receive the preliminary light output and ensure that the exit angle of the imaging chip group is less than 2 degrees to obtain pre-optimized light after passing through the fourth lens group; the third lens group is used to balance the chromatic aberration of the pre-optimized light after passing through the fourth lens group to obtain optimized light after passing through the third lens group; the aperture is used to control the intensity and shape of the optimized light to obtain uniform light output; the second lens group is used to balance aberration converging light and obtain light corrected by the second lens group through the uniform light output; the first lens group is used to balance spherical aberration and ensure the size of the projection image and obtain the final clear image light output through the light corrected by the second lens group to achieve the final projection imaging within the target distance; The first lens group includes: a first lens and a second lens; The second lens group includes: a third lens and a fourth lens; The third lens group includes: a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens; The fourth lens group includes the tenth lens and the eleventh lens.

[0007] Preferably, the fifth lens and the sixth lens are glued together to form a single component.

[0008] Preferably, the seventh lens and the sixth lens are glued together to form a single component.

[0009] Preferably, the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens, ninth lens, tenth lens and eleventh lens are all independent glass spherical lenses.

[0010] Preferably, the overall optical power of the first lens group is less than 0.

[0011] Preferably, the overall optical power of the second, third, and fourth lens groups is greater than 0.

[0012] Preferably, the focal length of the first lens group is any value between -27.033 mm and -22.97 mm.

[0013] Preferably, the focal length of the second lens group is any value between 49.6 mm and 55.91 mm.

[0014] Preferably, the focal length of the third lens group is any value between 61 mm and 67.02 mm.

[0015] Preferably, the focal length of the fourth lens group is any value between 114.0 mm and 151 mm.

[0016] The present invention discloses the following technical effects: This invention provides a high-definition lens for 3D printing. The invention features a simple architecture that meets the requirements of desktop 3D printing equipment. It achieves 4K resolution without using XPR; the relative illumination across the entire field of view is above 95%, and the MTF (Mean Transmission Format) is above 0.7 (125 lp / mm), resulting in excellent image quality. Distortion is within 0.1%, and TV distortion is within 0.05%, demonstrating excellent distortion correction. The RMS radius of the dot plot (<2µm) is much smaller than the pixel size (4µm), offering significant advantages for applications like 3D printing that emphasize spot size and energy concentration. The design wavelengths of 390nm, 405nm, and 415nm incorporate the wavelength fluctuations of actual light sources, making the lens design more closely aligned with real-world conditions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a high-definition lens structure for 3D printing provided in Embodiment 1 of the present invention; Figure 2 This is a layout diagram provided in Embodiment 1 of the present invention; Figure 3 This is a spatial frequency MTF diagram provided in Embodiment 1 of the present invention; Figure 4 This is a dot diagram provided in Embodiment 1 of the present invention; Figure 5 This is a field distortion diagram provided in Embodiment 1 of the present invention; Figure 6 This is a TV distortion diagram provided in Embodiment 1 of the present invention; Figure 7 This is a relative illumination diagram provided in Embodiment 1 of the present invention; Figure 8 This is a schematic diagram of brightness uniformity provided in Embodiment 1 of the present invention; Figure 9 This is a layout diagram provided in Embodiment 2 of the present invention; Figure 10 The first MTF chart provided in Embodiment 2 of the present invention corresponds to an object distance of 225 mm; Figure 11 The second MTF chart provided in Embodiment 2 of the present invention, wherein the second MTF chart corresponds to an object distance of 250 mm; Figure 12The third MTF chart provided in Embodiment 2 of the present invention, wherein the third MTF chart corresponds to an object distance of 275 mm; Figure 13 This is a dot diagram provided in Embodiment 2 of the present invention; Figure 14 This is a field distortion diagram provided in Embodiment 2 of the present invention; Figure 15 This is a TV distortion diagram provided in Embodiment 2 of the present invention; Figure 16 This is a relative illumination diagram provided in Embodiment 2 of the present invention; Figure 17 This is a layout diagram provided in Embodiment 3 of the present invention; Figure 18 The MTF diagram provided in Embodiment 3 of the present invention; Figure 19 This is a dot diagram provided in Embodiment 3 of the present invention; Figure 20 This is the field distortion diagram provided in Embodiment 3 of the present invention; Figure 21 This is a TV distortion diagram provided in Embodiment 3 of the present invention; Figure 22 This is a relative illumination diagram provided in Embodiment 3 of the present invention.

[0019] Figure label: 100 - First lens group, 200 - Second lens group, 300 - Aperture stop, 400 - Third lens group, 500 - Fourth lens group, 600 - Imaging chip group, L1 - First lens, L2 - Second lens, L3 - Third lens, L4 - Fourth lens, L5 - Fifth lens, L6 - Sixth lens, L7 - Seventh lens, L8 - Eighth lens, L9 - Ninth lens, L10 - Tenth lens, L11 - Eleventh lens. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1 As shown, the present invention provides a high-definition lens for 3D printing, comprising: The first lens group 100, the second lens group 200, the aperture 300, the third lens group 400, the fourth lens group 500, and the imaging chip group 600 are arranged sequentially along the optical axis from the object side to the image side. The imaging chip group 600 is used to emit light to obtain preliminary light output; the fourth lens group 500 is used to receive the preliminary light output and ensure that the emission angle of the imaging chip group 600 is less than 2 degrees to obtain pre-optimized light after passing through the fourth lens group 500; the third lens group 400 is used to balance the chromatic aberration of the pre-optimized light after passing through the fourth lens group 500 to obtain optimized light after passing through the third lens group 400; the aperture 300 is used to control the intensity and shape of the optimized light to obtain uniform light output; the second lens group 200 is used to balance aberration converging light and obtain light corrected by the second lens group 200 through the uniform light output; the first lens group 100 is used to balance spherical aberration and ensure the size of the projection image and obtain the final clear image light output through the light corrected by the second lens group 200, so as to achieve the final projection imaging within the target distance; The first lens group 100 includes: a first lens L1 and a second lens L2; The second lens group 200 includes: a third lens L3 and a fourth lens L4; The third lens group 400 includes: a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9; The fourth lens group 500 includes: the tenth lens L10 and the eleventh lens L11.

[0023] Furthermore, the fifth lens L5 and the sixth lens L6 are glued together into a single component.

[0024] Furthermore, the seventh lens L7 and the sixth lens L6 are glued together to form a single component.

[0025] Furthermore, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11 are all independent glass spherical lenses.

[0026] Specifically, the first lens group 100 comprises ≤2 independent glass spherical lenses, with an overall optical power of 1<0; The second lens group 200 contains ≤2 independent glass spherical lenses, with an overall optical power of 2>0; The third lens group 400 comprises ≤5 independent glass spherical lenses, with an overall optical power of 3>0; the fourth lens group 500 comprises ≤2 independent glass spherical lenses, with an overall optical power of 4>0; the imaging chip group 600 includes protective glass; wherein, the high-definition lens has an F-number of 1.0≤F≤1.1; wherein, the high-definition lens has a focal length f-number of 18≤f≤20.5; refractive index 1.60≤Nd≤1.91; Abbe number 37.2≤Vd≤61; the fourth lens group 500 includes independently movable lenses, and the back focal distance between the fourth lens group 500 and the imaging chip is adjustable; it also has the advantages of being compatible with the ultraviolet band, having good environmental stability, and being compatible with multiple object distances, and has a compact structure and high resolution.

[0027] Furthermore, the first lens group 100 includes ≤2 independent spherical glass lenses, and at least one of them is an aspherical lens; the third lens group 400 includes ≤5 independent spherical glass lenses, and at least one of them is an aspherical lens. Furthermore, the projection distance L of the high-definition lens is 200mm≤L≤300mm; The throw ratio of the high-definition lens is: 1.1 ≤ TR ≤ 1.35; The system focal length f of the high-definition lens is: 18mm≤f≤20.5mm; 0.765≤f / D≤0.87; Where f is the effective focal length of the multi-object distance compatible projection lens, in mm; D is the entrance pupil diameter, in mm; and TR is the projection ratio of the multi-object distance compatible projection lens.

[0028] Specifically, the first lens L1 is a convex-concave negative lens with a focal length f1 of -87.8mm < f1 < -87.5mm; the second lens L2 is a biconcave negative lens with a focal length f2 of -42.3mm < f2 < -42.0mm; the third lens L3 is a concave-convex positive lens with a focal length f3 of 126mm < f3 < 126.5mm; the fourth lens L4 is a biconvex positive lens with a focal length f4 of 93mm < f4 < 94mm; the tenth lens L10 is a convex-concave negative lens with a focal length f10 of -87.45mm < f10 < -87mm; and the eleventh lens L11 is a convex-concave positive lens with a focal length f11 of 40.5mm < f11 < 41mm.

[0029] Furthermore, the optical lens satisfies the following condition: 0.99 < f / EPND < 1.1; where EPND represents the aperture of the optical lens, and f represents the focal length of the optical lens system. When the above formula is satisfied, a reasonable balance between the large light transmission capacity and the large imaging surface of the lens can be achieved, allowing the lens aperture value F to reach 1.0, thus achieving a large aperture effect and effectively improving the overall projection brightness.

[0030] Furthermore, the focal length of the first lens group 100 is any value between -27.033 mm and -22.97 mm.

[0031] Furthermore, the focal length of the second lens group 200 is any value between 49.6 mm and 55.91 mm.

[0032] Furthermore, the focal length of the first lens group 100 is any value between 61mm and 67.02mm.

[0033] Furthermore, the focal length of the first lens group 100 is any value between 114.0 mm and 151 mm.

[0034] Furthermore, the high-definition lens also satisfies the following conditions: CRA < 2°, 3.6 < BFL < 4, TVDIST < 0.022%; where CRA is the angle between the principal ray and the optical axis at the maximum field of view of the high-definition lens on the imaging plane, BFL is the on-axis distance from the image side of the eleventh lens L11 to the imaging plane, in mm, and TVDIST is the TV distortion of the imaging plane.

[0035] Furthermore, the surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, and the eleventh lens L11 are all provided with anti-reflective coatings.

[0036] The brightness uniformity of the projected image from the high-definition lens is >97%. Each lens element in the high-definition lens satisfies: 2 < / T<16; where, Where is the effective optical aperture of the lens, and T is the center thickness of the lens; The high-definition lens uses a MicroLED chip with a size of 0.69 inches, a CRA ≤ 60°, and a resolution of 3980. 2160.

[0037] Furthermore, the optical parameters of each lens in the high-definition lens provided in this embodiment are shown in Table 1 below.

[0038] Table 1

[0039] The coefficients of each order of the aspherical lenses GM1 & GM9 are shown in Table 2: Table 2

[0040] The projection lens is derived based on the specific parameters of each lens mentioned above, such as... Figure 2 As shown.

[0041] like Figure 3 As shown, MTF (Modulation Transfer Function) is currently the most accurate and scientific evaluation standard for lenses. The vertical axis represents contrast ratio; the closer it is to 1, the better the lens image quality. The horizontal axis represents resolution, measured in line pairs per millimeter. The image source pixel size used in this embodiment is 4µm, corresponding to a design resolution of 125 line pairs per millimeter. Projection lenses generally require an MTF value of at least 0.3 for each field of view at the design resolution, while the MTF values ​​for each field of view in this embodiment are all above 0.7.

[0042] like Figure 4 As shown, Figure 4 This is a dot plot of the lens's various fields of view. The smaller the spot radius of each field of view, the better the image quality it represents. Generally, an RMS of less than the pixel size (4µm) across the entire field of view is considered excellent. In the embodiment of this application, the RMS across the entire field of view is less than 1.5µm, which is considered very excellent.

[0043] like Figure 5 As shown. Figure 5 The left image shows the field curvature evaluation chart, and the right image shows the distortion evaluation chart. The vertical axis represents the field of view of the lens. The horizontal axis of the field curvature chart represents the magnitude of the field curvature value, and the horizontal axis of the distortion chart represents the distortion value. Distortion is a very important indicator for projection lenses; generally, optical distortion needs to be controlled within 3%, while TV distortion needs to be controlled within 1%. Figure 6 As shown, the system distortion in this embodiment is within 0.03%, and the TV distortion is within 0.02%, indicating that the TV distortion of the system is excellent.

[0044] Figure 7 The image shows the relative illumination of the lens. The edge illumination reaches 99%, which results in excellent uniformity of the projection effect on the system's imaging surface. Figure 8 This is a brightness uniformity diagram of the lens's projected image area. The brightness uniformity reaches 97%, resulting in excellent uniformity of the projection effect on the system's imaging surface. The calculation formula is: Brightness uniformity = (L1 + L3 + L7 + L9) / 4 / L5; The main parameters of the high-definition lens are shown in Table 3.

[0045] Table 3

[0046] Furthermore, Example 2 is a multi-object distance 3D printed high-definition lens, and the optical parameters of each lens are shown in Table 4 below. Table 4

[0047] The coefficients of each order of the aspherical lenses GM1 & GM9 are shown in Table 5: Table 5

[0048] The main parameters of the high-definition lens provided in this embodiment 2 are shown in Table 6 below.

[0049] Table 6

[0050] The high-definition lens provided in this embodiment has a projection distance of 225mm to 275mm. According to the Layout 2D diagram, by adjusting the 8th and 17th surfaces in Table 1 (i.e., simultaneously adjusting the aperture stop 300 / 500 and the third lens group 400 / 300), clear imaging can be ensured within the projection distance range. The focal length will also change slightly, such as from 20.35mm to 20.38mm. Specific parameters are shown in Table 7. Table 7

[0051] The projection lens is derived from the specific parameters of each lens in Table 7 above, such as... Figure 8 As shown.

[0052] like Figure 9-11 As shown, MTF (Modulation Transfer Function) is currently the most accurate and scientific evaluation standard for lenses. The vertical axis represents contrast ratio; the closer it is to 1, the better the lens image quality. The horizontal axis represents resolution, measured in line pairs per millimeter. The image source pixel size used in this embodiment is 4µm, corresponding to a design resolution of 125 line pairs per millimeter. Projection lenses generally require an MTF value of at least 0.3 for each field of view at the design resolution, while in this embodiment 2, the MTF values ​​for each field of view corresponding to different object distances are all above 0.55.

[0053] Figure 12 This is a dot plot of the lens's various fields of view. The smaller the spot radius of each field of view, the better the image quality it represents. Generally, an RMS of less than the pixel size (4µm) across the entire field of view is considered excellent. In the embodiments of this application, the RMS across the entire field of view is less than 2µm, which is considered very excellent.

[0054] Figure 13 In the diagram, the left image shows the field curvature evaluation chart, and the right image shows the distortion evaluation chart. The vertical axis represents the field of view angle of the lens. The horizontal axis of the field curvature chart represents the magnitude of the field curvature value, and the horizontal axis of the distortion chart represents the distortion value. Distortion is a very important indicator for projection lenses; generally, optical distortion needs to be controlled within 3%, while TV distortion needs to be controlled within 1%. Figure 14 The system distortion of the embodiment shown in this application is within 0.03%, and the TV distortion is within 0.02%, indicating that the TV distortion of the system is excellent.

[0055] Furthermore, the lens has an effective focal length of 20.35mm and an F / NO. of 1.0; the lens uses a 0.69-inch MicroLED chip; the selected lens material has high transmittance for light with a wavelength of 405nm; the first and ninth lenses L9 are aspherical glass lenses, while the other lenses are spherical glass lenses.

[0056] Furthermore, the optical parameters of each lens element in the high-definition lens provided in Example 3 are shown in Table 8 below: Table 8

[0057] The coefficients of each order of the aspherical lenses GM1 and GM9 are shown in Table 9: Table 9

[0058] The main parameters of the 3D printing lens provided in this embodiment 3 are shown in Table 10 below: Table 10

[0059] The projection lens is derived based on the specific parameters of each lens mentioned above, such as... Figure 17 The objective lens system 2D layout is shown; like Figure 18 As shown, MTF (Modulation Transfer Function) is currently the most accurate and scientific evaluation standard for lenses. The vertical axis represents contrast ratio; the closer it is to 1, the better the lens image quality. The horizontal axis represents resolution, measured in line pairs per millimeter. The image source pixel size used in this embodiment is 4µm, corresponding to a design resolution of 125 line pairs per millimeter. Projection lenses generally require an MTF value of at least 0.3 for each field of view at the design resolution, while the MTF values ​​for each field of view in this embodiment are all above 0.6.

[0060] Figure 19 This is a dot plot of the lens's various fields of view. The smaller the spot radius of each field of view, the better the image quality it represents. Generally, an RMS of less than the pixel size (4µm) across the entire field of view is considered excellent. In the embodiments of this application, the RMS across the entire field of view is less than 2µm, which is considered very excellent.

[0061] like Figure 20-21 As shown, Figure 20In the diagram, the left image shows the field curvature evaluation chart, and the right image shows the distortion evaluation chart. The vertical axis represents the field of view angle of the lens. The horizontal axis of the field curvature chart represents the magnitude of the field curvature value, and the horizontal axis of the distortion chart represents the distortion value. Distortion is a very important indicator for projection lenses. Generally, optical distortion needs to be controlled within 3%, while TV distortion needs to be controlled within 1%. The system distortion of this embodiment is within 0.03%, and the TV distortion value is within 0.02%, indicating that the TV distortion of the system is excellent.

[0062] Figure 22 The image shows the relative illumination of the lens. The edge illumination reaches 99%, which results in excellent uniformity of the projection effect on the system's imaging surface.

[0063] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0064] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A high-definition lens for 3D printing, characterized in that, include: The first mirror group, the second mirror group, the aperture, the third mirror group, the fourth mirror group, and the imaging chip group are arranged sequentially along the optical axis from the object side to the image side. The imaging chip group is used to emit light to obtain preliminary light output; the fourth lens group is used to receive the preliminary light output and ensure that the exit angle of the imaging chip group is less than 2 degrees to obtain pre-optimized light after passing through the fourth lens group; the third lens group is used to balance the chromatic aberration of the pre-optimized light after passing through the fourth lens group to obtain optimized light after passing through the third lens group; the aperture is used to control the intensity and shape of the optimized light to obtain uniform light output; the second lens group is used to balance aberration converging light and obtain light corrected by the second lens group through the uniform light output; the first lens group is used to balance spherical aberration and ensure the size of the projection image and obtain the final clear image light output through the light corrected by the second lens group to achieve the final projection imaging within the target distance; The first lens group includes: a first lens and a second lens; The second lens group includes: a third lens and a fourth lens; The third lens group includes: a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens; The fourth lens group includes the tenth lens and the eleventh lens.

2. The high-definition lens for 3D printing according to claim 1, characterized in that, The fifth and sixth lenses are glued together into one component.

3. A high-definition lens for 3D printing according to claim 1, characterized in that, The seventh lens and the sixth lens are glued together to form a single component.

4. A high-definition lens for 3D printing according to claim 1, characterized in that, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, and the eleventh lens are all independent glass spherical lenses.

5. A high-definition lens for 3D printing according to claim 1, characterized in that, The overall optical power of the first lens group is less than 0.

6. A high-definition lens for 3D printing according to claim 1, characterized in that, The overall optical power of the second, third, and fourth lens groups is all greater than 0.

7. A high-definition lens for 3D printing according to claim 1, characterized in that, The focal length of the first lens group is any value between -27.033 mm and -22.97 mm.

8. A high-definition lens for 3D printing according to claim 1, characterized in that, The focal length of the second lens group is any value between 49.6 mm and 55.91 mm.

9. A high-definition lens for 3D printing according to claim 1, characterized in that, The focal length of the third lens group is any value between 61 mm and 67.02 mm.

10. A high-definition lens for 3D printing according to claim 1, characterized in that, The focal length of the fourth lens group is any value between 114.0 mm and 151 mm.

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