3D printing ray machine lens and projection equipment

Abstract

The embodiment of the invention provides a 3D printing ray machine lens and projection equipment. The 3D printing ray machine lens comprises a first lens group, a diaphragm and a second lens group which are sequentially arranged in the direction from an object plane to an image plane, and the first lens group comprises a first lens and a second lens which are arranged at an interval; the first lens is a positive lens, and the second lens is a negative lens. The second lens group comprises a third lens to a sixth lens which are sequentially and independently arranged along the main optical axis, and the optical center of the second lens is located on the main optical axis; the 3D printing ray machine lens further comprises a turning optical element, and the turning optical element is arranged at at least one of the following positions: between the first lens and the second lens, on the object plane side of the first lens; the turning optical element is configured to turn an optical path into a folded optical path, the 3D printing ray machine lens meets the condition that the optical total length L is smaller than or equal to 54 mm, and the air interval A between the first lens and the second lens accounts for 30%-40% of the optical total length L.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of optical imaging technology. More specifically, the embodiments of the present application relate to a 3D printing optical machine lens and a projection device. Background Art

[0002] In recent years, 3D printing technology (additive manufacturing) has completely revolutionized traditional processing methods through a layered and stacked digital manufacturing model. In the medical field, light-curing technology (such as SLA / DLP) has become the mainstream choice for dental restorations (crowns, implant guides, etc.) due to its high resolution (up to 10μm~25μm) and the maturity of biocompatible resin materials. As 3D printing technology penetrates into medical scenarios, dental chairside printing equipment needs to meet the immediate needs of integrated diagnosis and treatment, and accelerate the iteration towards miniaturization, precision, and high integration. However, existing technologies still have significant bottlenecks: Low equipment integration: Mainstream DLP optical machines need to maintain a long optical path (typically 60mm~80mm) to ensure light uniformity and energy density, resulting in a large optical machine module (200×150×100mm). The overall size is generally greater than 0.5m³, and it needs to be placed on an independent operating table. It is not compatible with dental treatment chairs (clinical space utilization rate is less than 42%).

[0003] Poor environmental stability: The thermal expansion coefficient of the aluminum alloy optical machine frame is high (23×10⁻ 6 / ℃), a 10℃ fluctuation in the operating room temperature can cause the optical path to shift, resulting in a deviation of the printed layer thickness exceeding ±8μm, affecting the edge fit of the restoration (the pass rate for the standard <80μm is only 68%).

[0004] Conflict between material performance and efficiency: High-precision printing relies on low-viscosity resin (<300cP), but clinical requirements must simultaneously meet strength (flexural modulus >2000MPa) and efficiency (single crown printing time <20min), posing severe challenges to optical-mechanical energy density (≥8mW / cm²) and thermal management.

[0005] Insufficient distortion control: At short object distances (<50mm), the distortion rate of conventional lens combinations is >3.5%, affecting printing accuracy (edge ​​error exceeds ±20μm). Summary of the Invention

[0006] The purpose of this application is to provide a new technical solution for 3D printing optical machine lenses and projection equipment.

[0007] In a first aspect, the present application provides a 3D printing optical machine lens, wherein the 3D printing optical machine lens comprises a first lens group, an aperture, and a second lens group arranged in sequence from the object plane to the image plane, wherein: The first lens group includes a first lens and a second lens that are spaced apart; the first lens is a positive lens, and the second lens is a negative lens; The second lens group includes a third lens, a fourth lens, a fifth lens, and a sixth lens independently arranged in sequence along the main optical axis, and the optical center of the second lens is located on the main optical axis; The 3D printing optical machine lens further includes a turning optical element, which is disposed at at least one of the following positions: between the first lens and the second lens; the object side of the first lens; The turning optical element is configured to turn the optical path to form a folded optical path. The 3D printing optical machine lens meets the following requirements: the total optical length L is less than or equal to 54 mm, and the air gap A between the first lens and the second lens accounts for 30% to 40% of the total optical length L.

[0008] Optionally, the total focal length F of the 3D printing optical machine lens satisfies: 8mm≤F≤9mm.

[0009] Optionally, an air gap A between the first lens and the second lens is: 12mm≤A≤15mm.

[0010] Optionally, the optical center of the first lens is located on the principal optical axis; or, The optical center of the first lens is located on a first optical axis, and the first optical axis is perpendicular to the main optical axis.

[0011] Optionally, the turning optical element is a reflector or a prism.

[0012] Optionally, the turning optical element includes: A first deflection element is provided on the object plane side of the first lens, and is used to deflect the light beam by 90 degrees; A second deflection element is provided between the first lens and the second lens, and is used to deflect the light beam by 90 degrees again so as to return to the main optical axis direction; The optical path of the 3D printing optical machine lens is configured as follows: A U-shaped folded optical path, where the image plane and the object plane are on the same side and the principal optical axis is perpendicular to the object plane; or A Z-folded optical path, in which the image plane and the object plane are located on different sides and the principal optical axis is perpendicular to the object plane.

[0013] Optionally, the first turning element and the second turning element are both reflectors or prisms.

[0014] Optionally, there is only one deflection optical element, which is used to deflect the light beam by 90° and return it to the main optical axis for transmission; The turning optical element is arranged on the object plane side of the first lens or between the first lens and the second lens; wherein the optical path of the 3D printing optical machine lens is configured as: an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90° and the main optical axis is parallel to the object plane.

[0015] Optionally, the refractive index nd1 of the first lens is 1.7-1.75; The refractive index nd2 of the second lens is 1.5~1.53.

[0016] Optionally, the third lens is a positive lens, and its temperature refractive index coefficient dn3 / dt3 is 3.5×10 -6 / ℃~6.5×10 -6 / ℃; The fourth lens is a negative lens, and its temperature refractive index coefficient dn3 / dt4 is -6×10 -6 / ℃~-7×10 -6 / ℃.

[0017] Optionally, the fifth lens and the sixth lens are both positive lenses.

[0018] Optionally, the refractive index of the third lens, the fifth lens and the sixth lens is 1.7-1.75, and the refractive index of the fourth lens is 1.487-1.53; A difference between the Abbe number of any one of the third lens, the fifth lens, and the sixth lens and the Abbe number of the fourth lens is greater than 25.

[0019] Optionally, the first to sixth lenses are all independently assembled glass lenses.

[0020] In a second aspect, the present application provides a projection device, comprising: The 3D printing optical machine lens of the first aspect; and An equivalent turning prism or a turning prism, a galvanometer and an image source are arranged in sequence along the reverse light path.

[0021] The beneficial effects of this application are: The 3D printing optical lens solution provided in this embodiment utilizes a positive and negative lens combination with negative distortion compensation in the first lens group. The first lens is a positive lens with a second surface specifically designed to introduce negative distortion. This, in conjunction with the second lens, a negative lens, effectively offsets lens distortion generated when imaging at short object distances (<50mm), significantly reducing distortion across the entire field of view and fully meeting the high-precision printing requirements for dental restorations. Furthermore, the 3D printing optical lens incorporates a folded optical path by incorporating a turning optical element. This design reduces the total optical length of the optical lens along the principal optical axis to less than 54mm and controls the air gap between the first and second lenses to 30%-40%, significantly reducing assembly sensitivity (relaxing tolerances to ±80μm). The optical solution provided in this embodiment not only achieves a high degree of integration for the 3D printing optical lens (reducing its volume to, for example, 60×60×40mm) but also significantly improves imaging accuracy. This makes it particularly well-suited for the demanding miniaturization and high-precision requirements of dental chairside 3D printing equipment.

[0022] Other features and advantages of the present specification will become apparent from the following detailed description of exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the specification and, together with the description, serve to explain the principles of the specification.

[0024] Figure 1 This is one of the structural diagrams of the 3D printing optical machine lens provided in an embodiment of the present application; Figure 2 This is the second structural diagram of the 3D printing optical machine lens provided in an embodiment of the present application; Figure 3 The third structural diagram of the 3D printing optical machine lens provided in the embodiment of the present application; Figure 4 This is the fourth structural diagram of the 3D printing optical machine lens provided in an embodiment of the present application; Figure 5 This is the fifth structural diagram of the 3D printing optical machine lens provided in the embodiment of the present application; Figure 6 This is a projection distortion diagram of the 3D printing optical machine lens provided in Example 1 of the present application; Figure 7 This is the MTF diagram of the 3D printing optical machine lens provided in Example 1 of the present application; Figure 8 Field curvature and distortion diagram of the 3D printing optical machine lens provided in Example 1 of the present application; Figure 9This is a projection distortion diagram of the 3D printing optical machine lens provided in Example 2 of the present application; Figure 10 This is the MTF diagram of the 3D printing optical machine lens provided in Example 2 of the present application; Figure 11 This is a diagram of the field curvature and distortion of the 3D printing optical machine lens provided in Example 2 of the present application.

[0025] Description of reference numerals: 1. First lens group; G1, first lens; S1, first surface; S2, second surface; G2, second lens; S3, third surface; S4, fourth surface; 2, second lens group; G3, third lens; G4, fourth lens; G5, fifth lens; G6, sixth lens; 3. Aperture; 4. Turning optical element; 41. Reflector; 42. Prism; 5. Equivalent turning prism; 6. Turning prism; 7. Galvanometer; 8. Image source. DETAILED DESCRIPTION

[0026] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0027] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0028] Techniques and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the techniques and equipment should be considered part of the specification.

[0029] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0030] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0031] The following describes in detail the 3D printing optical machine lens and projection equipment provided in the embodiments of the present application in conjunction with the accompanying drawings.

[0032] According to one embodiment of the present application, a 3D printing optical machine lens is provided. Figure 1 and 5The 3D printing optical lens comprises a first lens group 1, an aperture 3, and a second lens group 2, arranged sequentially from the object plane to the image plane. The first lens group 1 comprises a first lens G1 and a second lens G2, spaced apart from each other. The first lens G1 is a positive lens, and its second surface S2, near the aperture 3, is configured to produce negative distortion to compensate for the distortion of the entire 3D printing optical lens during short-distance projection. The second lens G2 is a negative lens. The second lens group 2 comprises a third lens G3, a fourth lens G4, a fifth lens G5, and a sixth lens G6, independently arranged sequentially along the principal optical axis, with the optical center of the second lens G2 located on the principal optical axis. The 3D printing optical machine lens further includes a turning optical element 4, which is disposed at at least one of the following positions: between the first lens G1 and the second lens G2, and on the object surface side of the first lens G1; the turning optical element 4 is configured to turn the optical path to form a folded optical path. The 3D printing optical machine lens satisfies the following requirements: the total optical length L is ≤ 54 mm, and the air space A between the first lens G1 and the second lens G2 accounts for 30% to 40% of the total optical length L.

[0033] The 3D printing optical-mechanical lens provided in the embodiments of this application, with its compact optical length (L ≤ 54mm) and high-precision imaging performance, demonstrates significant advantages in applications such as dental chairside 3D printing equipment. This demonstrates that the 3D printing optical-mechanical lens provided in this application, through its highly integrated design, is specifically designed to meet the stringent requirements for space efficiency and imaging accuracy in integrated diagnosis and treatment scenarios, making it particularly suitable for clinical environments with limited space, such as dental chairside cabinets.

[0034] By introducing one or two turning optical elements 4 into the optical path of the 3D printed optical lens (the total optical length of the entire 3D optical lens along the main optical axis is ≤54mm, and the volume of the optical lens is 60×60×40mm), and coordinating with the negative distortion compensation technology in the optical path (full field of view distortion rate <0.5%), the 3D printed optical lens provided in the embodiment of the present application can be seamlessly embedded in equipment with limited space, such as dental chair side cabinets, and can meet the ±15μm accuracy requirements of dental restorations (such as crowns and implant guides).

[0035] The technical characteristics of the 3D printing optical mechanical lens provided by the embodiments of this application also enable it to have cross-disciplinary application potential. For example, the application fields of the 3D printing optical mechanical lens include but are not limited to micro-nano manufacturing and precision machining, biomedical engineering, and portable 3D printing equipment.

[0036] The main components of the 3D printing optical machine lens provided in the embodiments of the present application are described in detail below.

[0037] The 3D printing optical machine lens provided in the embodiment of this application is shown in FIG. Figures 1 to 5The optical structure includes a first lens group 1 (located on the object side), which includes two lenses: a first lens G1 (positive lens) and a second lens G2 (negative lens).

[0038] The first lens G1 is designed as a positive lens, and its optical surface includes a first surface S1 away from the aperture 3 and a second surface S2 near the aperture 3. The second surface S2 is designed to have the ability to generate negative distortion. This is intended to effectively offset the distortion of the entire 3D printing optical machine lens caused by the close projection distance when imaging at short object distances (<50mm) after multiple changes in object distance during the 3D printing process by introducing a large negative TRANSVER distortion. This ensures that the distortion rate of the 3D printing optical machine lens provided in this application is less than 0.5% across the entire field of view, thereby meeting the ±15μm accuracy requirement for dental restorations (such as crowns and implant guides).

[0039] In addition, the spherical aberration, coma, field curvature and astigmatism coefficients of the first lens G1 are all controlled within a small range, and the impact of its tilt or decentering on the image quality of the overall optical machine lens is significantly reduced, providing a higher tolerance for subsequent assembly.

[0040] The second lens element G2 is designed as a negative lens. It combines with the first lens element G1 (a positive lens) to form a positive-negative lens combination optical structure. This combined optical structure not only further corrects aberrations such as spherical aberration and coma, but also achieves the following dual technical effects through the large air gap A between the two lenses (the air gap A accounts for 30% to 40% of the total optical length of the lens along the principal optical axis): (1) Space optimization: for subsequent turning light paths (such as U-shaped, Z-shaped, and L-shaped folding, see Figures 1 to 5 ) provides ample layout space to support the miniaturization design of 3D printed optical machine lenses; (2) Reducing assembly sensitivity: The large air gap A significantly reduces the assembly sensitivity between the first lens G1 and the second lens G2, and the tolerance can be relaxed to ±80 μm (5 to 8 times wider than the traditional design). This makes the assembly process of the turning optical element 4 and the first lens G1 and the second lens G2 easier to control, reduces the dependence on manual debugging experience, and reduces manufacturing costs.

[0041] In summary, the combined positive and negative optical powers of the first lens G1 and the second lens G2 in the first lens assembly 1, combined with negative distortion compensation, aberration correction, and reduced assembly sensitivity, overcome the contradiction between printing accuracy and product size in traditional printer lenses. In particular, this application provides a reliable optical solution for high-precision applications such as dental chairside 3D printing equipment.

[0042] The 3D printing optical machine lens provided in the embodiment of this application is shown in FIG. Figures 1 to 5 The optical structure also includes an aperture 3, which is located between the first lens group 1 and the second lens group 2. As a key beam control element, the aperture 3 mainly performs the following functions: Beam aperture control: By limiting the effective diameter of the incident beam, aperture 3 can effectively suppress interference from non-imaging light and prevent stray light from entering the 3D printer lens, thereby significantly improving the contrast of the displayed image and ensuring the clarity of the edges of the printed structure.

[0043] Collaborative optimization of aberration correction: The aperture 3 and the first lens group 1 (including the first lens G1 and the second lens G2) form an optical collaborative system. The position of the aperture 3 has been optimized through optical design, which can cooperate with the negative distortion compensation of the second surface S2 of the first lens G1 and the spherical aberration correction of the positive and negative lens combination of the first lens G1 and the second lens G2 to achieve a systematic balance of aberrations within the entire field of view.

[0044] Achieve compact structure: The introduction of the aperture 3 can also compress the size of the optical path along the main optical axis. The axial compression rate is greater than 50%, so that the volume of the entire 3D printing optical machine lens can be reduced to 60×60×40mm, thereby being able to adapt to the embedded installation requirements of the dental chair side cabinet.

[0045] It can be seen that, through the combination of the aperture 3 and the first lens group 1 , a balance is achieved between controlling stray light, correcting aberrations and achieving miniaturization.

[0046] The optical structure of the 3D printing optical machine lens provided in the embodiment of the present application is shown in FIG. Figures 1 to 5 , also includes a second lens group 2 located on the image side, primarily composed of third through sixth lenses G3, G6, independently arranged along the principal optical axis. This second lens group 2, acting as a convergent light group, forms a dispersion-compensating structure by differentially designing the refractive indices of each lens (for example, a negative lens with a refractive index of 1.487-1.53 ​​combined with a positive lens with a refractive index of 1.7-1.75) and Abbe numbers (the difference between the positive and negative Abbe numbers is >25). This optical design systematically corrects the residual spherical aberration (wavelength aberration <0.05λ) and field curvature (sag difference <0.02mm) of the optical lens, ensuring consistent image clarity across the entire field of view. This is particularly beneficial for precisely shaping the edge contours of dental restorations.

[0047] The coordinated optimization mechanism of the aperture 3, the first lens group 1 and the second lens group 2 is as follows: The aperture 3 controls the effective aperture of the incident light beam, achieving synergistic optimization with the negative distortion compensation of the first lens group 1 (negative TRANSVER distortion of the second surface S2 of the first lens element G1) and the aberration correction of the second lens group 2. This synergistic optimization design can improve the marginal fit pass rate of dental restorations from 68% to 92% at an accuracy of ±15μm, while ensuring that the MTF value of the 3D printing optical machine lens at a spatial frequency of 93lp / mm is greater than 0.7 (average value over the entire field of view), see Figure 7 This feature not only supports high-precision printing of dental chairside equipment (such as crown edge error <±15μm), but can also be extended to 3D molding of complex structures such as micro-mechanical parts, realizing cross-domain precision manufacturing applications.

[0048] The 3D printing optical machine lens provided in the embodiment of this application is shown in FIG. Figures 1 to 5 , a turning optical element 4 is specially introduced into its optical structure. Through this turning optical element 4 (reflector 41 or prism 42), the original straight optical path can be formed into a U-shaped / Z-shaped / L-shaped turn, thereby achieving the size compression of the optical path in the direction of the main optical axis. For example, this design can reduce the traditional 60mm~80mm main optical axis length to ≤53.8mm (including the DMD tilt compensation space), and the axial (the axial here refers to the main optical axis direction) compression rate reaches more than 51.8%, so that the volume of the whole machine can be optimized to a compact size of 60×60×40mm. This design allows the 3D printed optical machine lens to be seamlessly embedded in the dental chair side cabinet (standard accommodation space ≥100×70×50mm), with a space adaptation rate of over 97%, solving the problem of insufficient physical compatibility of equipment in clinical diagnosis and treatment environments.

[0049] The turning optical element 4 in the embodiment of the present application can achieve space compression by, for example, two-stage optical path turning. Figures 1 to 3 : First-stage deflection: A high-reflectivity deflection optical element 4 (e.g., reflectivity > 98% @ 405nm) with a 45° angle can be placed behind the second surface S2 of the first lens G1 to deflect the light beam 90° to a lateral optical path, thus breaking the dependence of the traditional straight-through optical path on axial space. Second stage folding: A second high reflectivity turning optical element 4 is set before the front surface of the second lens G2, i.e., the third surface S3. Its purpose is to deflect the light beam by 90° again, so that the light beam returns to the direction of the main optical axis, completing the Z-shaped or U-shaped folding of the light path, respectively. Figures 1 to 3 .in, Figure 1 and Figure 3 The U-folded optical path is shown. Figure 2 Shown is a Z-folded optical path.

[0050] The 3D printing optical lens provided in the embodiments of the present application utilizes a positive and negative lens combination with negative distortion compensation in the first lens group 1: the first lens G1 is a positive lens, and its second surface S2 is specially designed to introduce negative distortion. This, in conjunction with the second lens G2, which functions as a negative lens, effectively offsets the lens distortion generated when imaging at short object distances (<50mm), ensuring a significantly reduced distortion rate across the entire field of view, fully meeting the requirements for high-precision printing of dental restorations. Furthermore, the 3D printing optical lens utilizes a folded optical path by introducing a turning optical element 4. This design can reduce the total optical length of the 3D printing optical lens along the principal optical axis to less than 54mm, and control the air gap A between the first lens G1 and the second lens G2 to 30% to 40%. This significantly reduces assembly sensitivity (relaxing the tolerance to ±80μm).

[0051] The optical solution provided by the embodiments of this application not only achieves a high degree of integration of the 3D printing optical machine lens, reducing its size to, for example, 60×60×40mm, but also significantly improves imaging accuracy. This is particularly suitable for the stringent requirements of miniaturization and high precision for dental chairside 3D printing equipment.

[0052] In some examples of the present application, the total focal length F of the 3D printing optical machine lens satisfies: 8mm≤F≤9mm.

[0053] In the example of this application, the total focal length range of the 3D printing optical machine lens can match the design of a 0.16-inch to 0.23-inch DMD chip (i.e., the diagonal size of the DMD chip is 4.06mm to 5.86mm), which can achieve a projection optical system TRO (throw ratio) of 1.3 to 1.6. This ratio ensures that the light beam can still fully cover the effective imaging area of ​​the DMD chip at a short object distance (<50mm), avoiding the edge image quality degradation (such as field curvature error >30μm) caused by beam divergence in traditional long-focal-length solutions (focal length >12mm), or the reduction in printing efficiency caused by insufficient light energy density in short-focal-length solutions.

[0054] Within the 8mm-9mm focal length range, a large negative TRANSVER design, introduced through the second surface S2 of the first lens element G1, effectively offsets nonlinear distortion during short-object-distance imaging, achieving a distortion rate of <0.5% (F-Theta nonlinear error <0.05%) across the entire field of view. Compared to traditional long-focal-length solutions (focal length >12mm), this design reduces field curvature error at the edges of the field of view from >30μm to <8μm, significantly improving the success rate of printing complex structures such as micro-mechanical parts.

[0055] This compact focal length design provides key parameters for optical path turning in optical machine lenses. Specifically: When the total focal length F of the 3D printing optical machine lens is 8mm~9mm, combined with the U-shaped or Z-shaped folded optical path design, see Figures 1 to 3 , compressing the original 103.8mm optical path to approximately 50mm, achieving an axial compression ratio of 51.8%, and reducing the overall device volume to 60×60×40mm. This size allows the 3D printed optical machine lens to be directly embedded in the side cabinet of a dental treatment chair (standard storage volume ≥≥100×70×50mm), solving the problem of insufficient physical compatibility of equipment in the diagnosis and treatment environment.

[0056] In a total focal length design of 8mm to 9mm, by increasing the air gap A between the first lens G1 and the second lens G2 (accounting for 30% to 40% of the total optical length L), assembly sensitivity can be significantly reduced. For example, the assembly tolerance is relaxed from the traditional ±10μm to ±80μm. At the same time, by optimizing the optical path, the optical lens MTF@93lp / mm>0.7 (average value over the entire field of view) is maintained. Figure 7 .

[0057] In some examples of the present application, the air gap A between the first lens G1 and the second lens G2 is: 12 mm ≤ A ≤ 15 mm.

[0058] In the example provided in this application, by designing the air gap A between the first lens G1 and the second lens G2 to be 12 mm to 15 mm, combined with the turning optical path design (introducing the turning optical element 4 to form a folded optical path), the coordinated optimization of optical performance and assembly compatibility is achieved.

[0059] In this embodiment, the air gap A is relatively large. This design can reduce the sensitivity of the 3D printer's optical lens to internal lens eccentricity and tilt. In traditional compact optical paths, the spacing between lenses must be controlled within ±10μm, otherwise image quality (such as MTF value) will be reduced.

[0060] This application uses a large air gap A design, such as an air gap A of 12mm~15mm, to relax the assembly tolerance to ±80μm, which helps reduce manufacturing costs and improve yield. At the same time, through optical path optimization, the optical machine lens MTF@93lp / mm>0.7 (full field average) is maintained. Figure 7 .

[0061] In some examples of this application, see Figure 5 , the optical center of the first lens G1 is located on the principal optical axis; or, see Figures 1 to 4 , the optical center of the first lens G1 is located on the first optical axis, and the first optical axis is perpendicular to the main optical axis.

[0062] See also Figures 1 to 4, the first lens G1 and the second lens G2 are arranged along different optical axes, and their optical axes are perpendicular to each other. Specifically, the optical axes of the first lens G1 and the second lens G2 are perpendicular and intersect at a point O. In this case, the air gap A between the first lens G1 and the second lens G2 is the sum of the distance A1 from the optical center of the second surface S2 of the first lens G1 to point O and the distance A2 from the optical center of the third surface S3 of the second lens G2 to point O.

[0063] See also Figure 5 The first lens G1 and the second lens G2 are spaced apart along the same optical axis, that is, both the first lens G1 and the second lens G2 are spaced apart along the principal optical axis. In this case, the air gap A between the first lens G1 and the second lens G2 is the distance between the optical centers of the second surface S2 and the third surface S3, two adjacent surfaces of the two lenses.

[0064] In some examples of this application, see Figures 1 to 5 The turning optical element 4 is a reflector 41 or a prism 42 .

[0065] The reflector 41 can achieve directional deflection of the light beam by, for example, applying a high-reflectivity coating (reflectivity > 98% @ 405nm). For example, in the optical path design provided herein, the reflector 41 can deflect the incident light beam by 90° (as in the first-stage deflection) or by 90° in the opposite direction (as in the second-stage return), thereby compressing the axial space (along the main optical axis) of the 3D printing optical machine lens.

[0066] The deflection optical element 4 is, for example, a plane reflector tilted at 45°, and a high-reflectivity coating may be applied to the mirror surface.

[0067] Of course, the prism 42 can also realize the deflection of the light beam.

[0068] The prism 42 is, for example, a right-angled triangular prism, and its reflecting surface is an inclined surface.

[0069] By designing the light beam deflection of the reflector 41 or the prism 42, the size of the 3D printing optical machine lens provided in the embodiment of the present application can be compressed from the traditional 200×150×100mm to 60×60×40mm, which is suitable for the side cabinet of the dental treatment chair (standard accommodation volume ≥100×70×50mm).

[0070] In some examples of this application, see Figures 1 to 3The deflection optical element 4 includes two deflection elements: a first deflection element and a second deflection element. The first deflection element is arranged on the object side of the first lens G1, and is used to deflect the light beam by 90°; the second deflection element is arranged between the first lens G1 and the second lens G2, and is used to deflect the light beam by another 90° so that it returns to the main optical axis direction. The optical path of the 3D printing optical machine lens is configured as: a U-shaped folded optical path or a Z-shaped folded optical path. Figure 1 and Figure 3 , for the U-shaped folded optical path, the image plane and the object plane are located on the same side and the principal optical axis is perpendicular to the object plane. Figure 2 For the Z-folded optical path, the image plane and the object plane are located on different sides and the main optical axis is perpendicular to the object plane.

[0071] In the example provided in this application, see Figures 1 to 3 By introducing a double turning element into the 3D printing optical machine lens, namely the first turning element and the second turning element, a U-shaped or Z-shaped folded optical path design can be formed, thereby achieving the compactness of the 3D printing optical machine lens structure and the high-precision coordinated optimization of the optical performance.

[0072] Specifically, see Figures 1 to 3 The first deflection element is located on the object side of the first lens G1. Its core function is to deflect the incident light beam by 90° and direct it laterally into the subsequent optical path. The second deflection element, located between the first lens G1 and the second lens G2, deflects the light beam by another 90° back toward the principal optical axis, forming a closed optical path. The double deflection element achieves a 180° turn of the light beam through two orthogonal deflections, compressing the axial (principal optical axis) space.

[0073] For example, in a U-shaped folded optical path, the first turning element turns the light beam from longitudinal to transverse, and the second turning element turns it back to longitudinal, forming a "U"-shaped path, see Figure 1 and Figure 3 .

[0074] Please continue to see Figure 1 and Figure 3 The design features of the U-shaped folded optical path are as follows: (1) The structure is configured as follows: the image plane and the object plane are on the same side, and the principal optical axis is perpendicular to the object plane.

[0075] (2) The optical path is as follows: the light beam is deflected 90° by the first turning element and then transmitted horizontally, passes through the first lens G1 and the second lens G2, and then deflected 90° in the opposite direction by the second turning element to return to the main optical axis.

[0076] With the U-shaped folded optical path design, the total length from the object plane to the image plane is compressed from 103.8mm to 50mm (including the DMD tilt compensation space), with a compression rate of 51.8%.

[0077] For example, in a Z-fold optical path, the first turning element turns the light beam from longitudinal to transverse, and the second turning element turns it back to longitudinal. Since the object plane is located on a different side of the image plane, a Z-shaped path is formed, see Figure 2 .

[0078] Please continue to see Figure 1 and Figure 3 The design features of the U-shaped folded optical path are as follows: (1) The structural configuration is as follows: the image plane and the object plane are located on different sides, and the principal optical axis is perpendicular to the object plane.

[0079] (2) The optical path is as follows: the light beam is deflected 90° by the first turning element and then transmitted horizontally, passes through the first lens G1 and the second lens G2, and then deflected 90° by the second turning element and transmitted along the main optical axis to the opposite side image plane.

[0080] It should be noted that, through the Z-shaped bend, the length of the 3D optical machine lens provided in this application can be further compressed.

[0081] In some examples of this application, see Figures 1 to 3 The first turning element and the second turning element both use a reflector 41 or a prism 42 .

[0082] In one example, see Figure 1 The deflection optical element 4 includes two deflection elements: a first deflection element and a second deflection element. The first deflection element is disposed on the object side of the first lens G1 and is used to deflect the light beam by 90°. The second deflection element is disposed between the first lens G1 and the second lens G2 and is used to deflect the light beam by another 90°, thereby returning it to the direction of the principal optical axis. Both the first deflection element and the second deflection element are reflectors 41. The optical path of the 3D printing optical engine lens is configured as a U-shaped folded optical path, in which the image plane and the object plane are located on the same side and the principal optical axis is perpendicular to the object plane.

[0083] In one example, see Figure 2The deflection optical element 4 includes two deflection elements: a first deflection element and a second deflection element. The first deflection element is disposed on the object side of the first lens G1 and is used to deflect the light beam by 90°. The second deflection element is disposed between the first lens G1 and the second lens G2 and is used to deflect the light beam by another 90°, thereby returning it to the direction of the principal optical axis. Both the first deflection element and the second deflection element are prisms 42. The optical path of the 3D printing optical engine lens is configured as a Z-fold optical path, in which the image plane and the object plane are located on different sides and the principal optical axis is perpendicular to the object plane.

[0084] In one example, see Figure 3 The deflection optical element 4 includes two deflection elements: a first deflection element and a second deflection element. The first deflection element is disposed on the object side of the first lens G1 and is used to deflect the light beam by 90°. The second deflection element is disposed between the first lens G1 and the second lens G2 and is used to deflect the light beam by another 90° so that it returns to the direction of the principal optical axis. Both the first deflection element and the second deflection element are prisms 42. The optical path of the 3D printing optical engine lens is configured as a U-shaped folded optical path, in which the image plane and the object plane are located on the same side and the principal optical axis is perpendicular to the object plane.

[0085] In some examples of this application, see Figure 4 and Figure 5 , there is only one deflection optical element 4, which is used to deflect the light beam 90° and return it to the direction of the main optical axis for transmission; the deflection optical element 4 is arranged on the object plane side of the first lens G1 or between the first lens G1 and the second lens G2; wherein, the optical path of the 3D printing optical machine lens is configured as: an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90° and the main optical axis is parallel to the object plane.

[0086] This application also achieves further compactness and optimization of optical performance of 3D printing optical machine lens by introducing an L-shaped folded optical path design of a single turning element (reflector 41 or prism 42) into the 3D printing optical machine lens. Figure 4 and Figure 5 .

[0087] In the example provided in this application, only one deflection optical element 4 is introduced. It can be a high-reflectivity mirror 41 (reflectivity > 98% @ 405nm) or a prism 42 (such as a right-angled triangular prism). It can be placed on the object side of the first lens G1 or between the first lens G1 and the second lens G2. The core function of this single deflection optical element 4 is to deflect the light beam from the longitudinal main optical axis to the lateral direction through a single 90° deflection, and then converge it to the image plane through the subsequent second lens group 2, forming an "L"-shaped optical path. Figure 4 and Figure 5 .

[0088] In one example, see Figure 4 , there is only one deflection optical element 4, which is a reflector 41, used to deflect the light beam 90° and return it to the direction of the main optical axis for transmission. The deflection optical element 4 is arranged between the first lens G1 and the second lens G2; wherein, the optical path of the 3D printing optical machine lens is configured as: an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90° and the main optical axis is parallel to the object plane.

[0089] In one example, see Figure 5 , there is only one deflection optical element 4, which is a prism 42, used to deflect the light beam 90° and return it to the direction of the main optical axis for transmission. The deflection optical element 4 is arranged on the object plane side of the first lens G1; wherein, the optical path of the 3D printing optical machine lens is configured as: an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90° and the main optical axis is parallel to the object plane.

[0090] Through the L-shaped turn, the length of the 3D optical machine lens provided by this application is further compressed.

[0091] In some examples of the present application, the refractive index nd1 of the first lens G1 is 1.7~1.75.

[0092] The refractive index nd2 of the second lens G2 is 1.5~1.53.

[0093] The first lens element G1 is a positive lens with a high refractive index nd1 of 1.7 to 1.75. For example, the first lens element G1 is made of heavy flint glass, such as H-ZBAF21 or H-LAF4GT. Its high refractive index enhances light convergence and introduces negative distortion (transverse distortion coefficient -0.8% to -1.2%) through its second surface S2, offsetting imaging distortion at short object distances (less than 50mm).

[0094] The second lens G2 is a negative lens with a low refractive index nd2 of 1.5 to 1.53. For example, the second lens G2 is made of light flint glass, such as H-FK61 or H-QK3L. Its low refractive index reduces light deflection angles, and together with the first lens G1, it forms a positive-negative lens combination that balances aberrations across the entire optical machine lens.

[0095] Specifically, the first lens G1 and the second lens G2 form a positive-negative lens combination: the first lens G1 is a positive lens (with a refractive index of 1.7-1.75), and the second lens G2 is a negative lens (with a refractive index of 1.5-1.53). The air gap A between the two lenses is designed to be 12-15 mm (accounting for 30-40% of the total system length). The large air gap A provides space for the subsequent deflection of the optical path and also makes the spacing between the first and second lenses G1 and G2 insensitive. The first lens G1 has very low spherical aberration, coma, field curvature, and astigmatism coefficients. Its tilt and decentration have little impact on the image quality of the entire 3D printing optical machine lens, meeting the assembly tolerance requirements of the deflection optical element 4 and the first lens G1. A large negative TRANSVER distortion is introduced through the second surface S2 of the first lens G1 to offset imaging distortion at short object distances.

[0096] In some examples of this application, see Figures 1 to 5 The third lens G3 is a positive lens, and its temperature refractive index coefficient dn3 / dt3=3.5~6.5×10 -6 / ℃; the fourth lens G4 is a negative lens, and its temperature refractive index coefficient dn3 / dt4=-6~-7×10 -6 / ℃.

[0097] In the example of this application, the third lens G3 is designed as a positive lens, and its temperature refractive index coefficient dn3 / dt3=3.5~6.5×10 -6 / ℃, the fourth lens G4 is designed as a negative lens, and its temperature refractive index coefficient dn3 / dt4=-6~-7×10 -6 / ℃, the combination of the two realizes the focal plane stability of the 3D printed optical machine lens in the temperature range of -20℃ to 80℃ (the offset is less than ±3μm).

[0098] The third lens G3 is a positive lens, whose positive temperature refractive index coefficient (dn / dt) increases significantly with increasing temperature, enhancing the light converging ability and compensating for the thermal expansion of the aluminum alloy lens barrel (used to accommodate each lens) (CTE = 2.35×10⁻ 6 / ℃).

[0099] The fourth lens G4 is a negative lens whose negative temperature refractive index coefficient (dn4 / dt4) reduces the light deflection angle as the temperature rises. It forms an inverse compensation pair with the third lens G3, thereby offsetting the linear expansion of the aluminum alloy frame.

[0100] When the ambient temperature rises, the dn / dt of the third lens element G3 shortens the focal length, while the dn / dt of the fourth lens element G4 lengthens the focal length. The combined focal length changes offset the expansion of the lens barrel. When the ambient temperature drops, the reverse process occurs, ensuring that the focal plane offset is less than ±3μm.

[0101] In some examples of this application, see Figures 1 to 5 The fifth lens G5 and the sixth lens G6 are both positive lenses.

[0102] In the optical path of the 3D printing optical machine lens of the embodiment of the present application, the fifth lens G5 and the sixth lens G6 are sequentially located at the ends of the optical path (close to the image plane). Through the converging effect, the total length from the object plane to the image plane of the entire projection device is compressed from 103.8 mm to 53.8 mm (including the DMD tilt compensation space), and the axial compression rate can reach 51.8%.

[0103] See also Figure 7 According to the MTF performance test: at a spatial frequency of 93lp / mm, the MTF of the 3D printing optical machine lens provided by the embodiment of the present application has an average value of >0.7 over the entire field of view, which is 40% higher than the traditional design (MTF <0.5), meeting the ISO 12836 standard requirements for dental restoration accuracy (±15μm).

[0104] In some examples of the present application, the refractive index of the third lens G3, the fifth lens G5, and the sixth lens G6 is 1.7-1.75, and the refractive index of the fourth lens G4 is 1.487-1.53; and the difference between the Abbe number of any one of the third lens G3, the fifth lens G5, and the sixth lens G6 and the Abbe number of the fourth lens G4 is greater than 25.

[0105] The present application achieves correction of spherical aberration (residual wave aberration <0.05λ) and field curvature (maximum sag difference <0.02mm) by setting the refractive index of the third lens G3, the fifth lens G5 and the sixth lens G6 to 1.7~1.75 and the Abbe number vd≈34; setting the refractive index of the fourth lens G4 to 1.487~1.53 and the Abbe number vd≈65; and utilizing the characteristic that the Abbe number difference between the lenses is greater than 25.

[0106] This combination of an Abbe number difference greater than 25 results in minimal axial and lateral chromatic aberration in the optical lens, meeting the color reproduction requirements of dental restorations (biocompatible resin materials require precise control of the curing wavelength).

[0107] In some examples of this application, see Figures 1 to 5 The first lens G1 to the sixth lens G6 are all independently assembled glass lenses.

[0108] This application solves the aging risk, high assembly sensitivity and transmittance attenuation problems of traditional cemented lenses in 3D printing optical machines by designing the first lens G1 to the sixth lens G6 as independently assembled all-glass lenses, combining a non-cemented structure with material optimization.

[0109] Traditionally, bonded lenses are typically connected using UV-cured adhesive. However, the UV light introduced during 3D printing can accelerate the aging of the adhesive layer between the lenses. This application eliminates this aging risk by designing an all-glass, independently assembled lens assembly. This glue-free structure effectively prevents UV adhesive delamination and yellowing, achieving a transmittance of >99.2% at 405nm.

[0110] According to another embodiment of the present application, a projection device is provided. Figures 1 to 5 The projection device includes: the 3D printing optical machine lens as described above, and an equivalent turning prism 5 or a turning prism 6, a galvanometer 7 and an image source 8 arranged in sequence along the reverse light path.

[0111] Among them, the image source 8 is used to generate projection light, and the projection light is sequentially projected to the 3D printing optical machine lens through the galvanometer 7, the equivalent turning prism 5 or the turning prism 6, and forms a projection picture through the 3D printing optical machine lens and is presented on the projection screen.

[0112] The galvanometer 7 , the equivalent turning prism 5 , the turning prism 6 and the image source 8 can adopt existing technologies, and their structures and working principles are not described here in detail.

[0113] The projection device provided in the embodiment of the present application adopts the 3D printing optical machine lens described above, which can be matched with the 0.16-inch to 0.23-inch DMD chip in DLP technology. The TRO of the optical machine lens can reach 1.3 to 1.6, with small optical distortion, good imaging, and high projection quality.

[0114] The specific implementation of the projection device of the embodiment of the present application can refer to the various embodiments of the above-mentioned 3D printing optical machine lens, so it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0115] The optical structure of the 3D printing optical machine lens provided in the embodiment of this application can be found in Figures 1 to 5 As shown, the 3D printing optical machine lens can be Figures 1 to 5 The following describes the 3D printing optical machine lens in detail through Examples 1 and 2.

[0116] Example 1 The optical frame of the 3D printing optical machine lens provided in this application can be Figures 1 to 5Any one of them, and the optical parameter design of the 3D printing optical machine lens is shown in Table 1 and Table 2, wherein Table 2 is the primary Seidel coefficient of the optical surface of each lens shown in Table 1.

[0117] Combining the optical parameters shown in Table 1 and Table 2, Figures 6 to 8 The optical performance diagram of the 3D printing optical machine lens provided in this embodiment 1 is shown. Specifically, see Figure 7 , Figure 7 The MTF value shown in is: MTF@93lp / mm>0.7 (average value for the entire field of view). Figure 6 and Figure 8 The distortion correction effect is: full field distortion rate <0.5% (F-Theta nonlinear error <0.05%), which fully meets the ISO 12836 standard.

[0118] Continuing with Tables 1 and 2, the integrated dimensions of the 3D printing optical engine lens provided in Example 1 are only 60mm × 60mm × 40mm (L × W × H). This size allows the 3D printing optical engine lens to be embedded in a dental chair side cabinet (the dental chair side cabinet's accommodation space is ≥ 100mm × 70mm × 50mm).

[0119] It should be noted that Table 2 illustrates how a large air gap A provides space for the subsequent deflection optical path, while also making the spacing between the first lens element G1 and the second lens element G2 insensitive. Specifically, the first lens element G1 exhibits very low spherical aberration, coma, field curvature, and astigmatism coefficients. Its tilt and decentering have minimal impact on the image quality of the entire 3D printing optical machine lens, thus meeting the required assembly tolerances for the deflection optical element 4 and the first lens element G1. A significant negative TRANSVER distortion is introduced through the second surface S2 of the first lens element G1 to offset imaging distortion at short object distances.

[0120] Table 1

[0121] Table 2

[0122] Example 2 The optical frame of the 3D printing optical machine lens provided in this application can be Figures 1 to 5 Any one of them, and the optical parameter design of the 3D printing optical machine lens is shown in Table 3 and Table 4, wherein Table 4 is the primary Seidel coefficient of the optical surface of each lens shown in Table 3.

[0123] Combining the optical parameters shown in Table 3 and Table 4, Figures 9 to 11 The optical performance diagram of the 3D printing optical machine lens provided in this embodiment 2 is shown. Specifically, see Figure 10 , Figure 10 The MTF value shown in is: MTF@93lp / mm>0.75 (average value for the entire field of view). Figure 9 and Figure 11 The distortion correction effect is: full field distortion rate <0.5% (F-Theta nonlinear error <0.05%), which fully meets the ISO 12836 standard.

[0124] Continuing with Tables 3 and 4, the integrated dimensions of the 3D printing optical engine lens provided in Example 2 are also only: 60mm × 60mm × 40mm (L × W × H). This size allows the 3D printing optical engine lens to be embedded in a dental chair side cabinet (the dental chair side cabinet's storage space is ≥ 100mm × 70mm × 50mm).

[0125] It should be noted that Table 4 illustrates how a large air gap A provides space for the subsequent deflection optical path, while also making the spacing between the first lens element G1 and the second lens element G2 insensitive. Specifically, the first lens element G1 exhibits very low spherical aberration, coma, field curvature, and astigmatism coefficients. Its tilt and decentering have minimal impact on the image quality of the entire 3D printing optical machine lens, thus meeting the required assembly tolerances for the deflection optical element 4 and the first lens element G1. A significant negative TRANSVER distortion is introduced through the second surface S2 of the first lens element G1 to offset imaging distortion at short object distances.

[0126] Table 3

[0127] Table 4

[0128] The above embodiments focus on the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. Considering the simplicity of the text, they will not be repeated here.

[0129] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above examples may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A 3D printing optical machine lens, characterized in that: It comprises a first lens group (1), an aperture (3) and a second lens group (2) which are arranged in sequence from the object plane to the image plane, wherein: The first lens group (1) comprises a first lens (G1) and a second lens (G2) which are arranged at intervals; the first lens (G1) is a positive lens, and the second lens (G2) is a negative lens; The second lens group (2) comprises a third lens (G3), a fourth lens (G4), a fifth lens (G5) and a sixth lens (G6) which are independently arranged in sequence along the main optical axis, and the optical center of the second lens (G2) is located on the main optical axis; The 3D printing optical machine lens further comprises a turning optical element (4), wherein the turning optical element (4) is arranged at at least one of the following positions: between the first lens (G1) and the second lens (G2); the object side of the first lens (G1); The turning optical element (4) is configured to turn the optical path to form a folded optical path, and the 3D printing optical machine lens meets the following conditions: the total optical length L is less than or equal to 54 mm, and the air gap A between the first lens (G1) and the second lens (G2) accounts for 30% to 40% of the total optical length L.

2. The 3D printing optical machine lens according to claim 1, characterized in that: The total focal length F of the 3D printing optical machine lens satisfies: 8mm≤F≤9mm.

3. The 3D printing optical machine lens according to claim 1, characterized in that: The air gap A between the first lens (G1) and the second lens (G2) is: 12mm≤A≤15mm.

4. The 3D printing optical machine lens according to claim 3, characterized in that: The optical center of the first lens (G1) is located on the principal optical axis; or The optical center of the first lens (G1) is located on a first optical axis, and the first optical axis is perpendicular to the main optical axis.

5. The 3D printing optical machine lens according to any one of claims 1 to 4, characterized in that: The turning optical element (4) adopts a reflector (41) or a prism (42).

6. The 3D printing optical machine lens according to claim 5, characterized in that: The turning optical element (4) comprises: a first deflection element, arranged on the object surface side of the first lens (G1), for deflecting the light beam by 90°; A second deflection element is provided between the first lens (G1) and the second lens (G2), and is used to deflect the light beam by 90° again so as to return to the main optical axis direction for transmission; The optical path of the 3D printing optical machine lens is configured as follows: A U-shaped folded optical path, where the image plane and the object plane are on the same side and the principal optical axis is perpendicular to the object plane; or A Z-folded optical path, in which the image plane and the object plane are located on different sides and the principal optical axis is perpendicular to the object plane.

7. The 3D printing optical machine lens according to claim 6, characterized in that: The first turning element and the second turning element both use a reflector (41) or a prism (42).

8. The 3D printing optical machine lens according to claim 5, characterized in that: The deflection optical element (4) is provided with only one, and is used to deflect the light beam by 90° and return it to the main optical axis for transmission; The turning optical element (4) is arranged on the object plane side of the first lens (G1) or between the first lens (G1) and the second lens (G2); wherein the optical path of the 3D printing optical machine lens is configured as an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90 degrees and the main optical axis is parallel to the object plane.

9. The 3D printing optical machine lens according to claim 5, characterized in that: The refractive index nd1 of the first lens (G1) is 1.7-1.75; The refractive index nd2 of the second lens (G2) is 1.5-1.

53.

10. The 3D printing optical machine lens according to claim 5, characterized in that: The third lens (G3) is a positive lens, and its temperature refractive index coefficient dn3 / dt3 is 3.5×10 -6 / ℃~6.5×10 -6 / ℃; The fourth lens (G4) is a negative lens, and its temperature refractive index coefficient dn3 / dt4 is -6×10 -6 / ℃~-7×10 -6 / ℃.

11. The 3D printing optical machine lens according to claim 10, characterized in that: The fifth lens (G5) and the sixth lens (G6) are both positive lenses.

12. The 3D printing optical machine lens according to claim 11, characterized in that: The refractive index of the third lens (G3), the fifth lens (G5) and the sixth lens (G6) is 1.7-1.75, and the refractive index of the fourth lens (G4) is 1.487-1.53; The difference between the Abbe number of any one of the third lens (G3), the fifth lens (G5) and the sixth lens (G6) and the Abbe number of the fourth lens (G4) is greater than 25.

13. The 3D printing optical machine lens according to claim 5, characterized in that: The first lens (G1) to the sixth lens (G6) are all independently assembled glass lenses.

14. A projection device, characterized in that: include: The 3D printing optical machine lens according to any one of claims 1 to 13; as well as An equivalent turning prism (5) or a turning prism (6), a galvanometer (7), and an image source (8) are sequentially arranged along the reverse light path.

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