A 3D printing optical engine lens and projection device

Abstract

This application provides a 3D printing optical engine lens and a projection device. The 3D printing optical engine lens includes a first lens group, an aperture, and a second lens group arranged sequentially from the object plane to the image plane. The first lens group includes a first lens and a second lens arranged at intervals. The first lens is a positive lens, and the second lens is a negative lens. The second lens group includes a third to a sixth lens arranged independently along the principal optical axis, and the optical center of the second lens is located on the principal optical axis. The 3D printing optical engine lens also includes a reversing optical element, which is disposed at least at one of the following locations: between the first and second lenses, or on the object plane side of the first lens. The reversing optical element is configured to revers the optical path to form a folded optical path. The 3D printing optical engine lens satisfies the following: the total optical length L ≤ 54 mm, and the air gap A between the first and second lenses accounts for 30% to 40% of the total optical length L.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, and more specifically, to a 3D printing optical engine lens and projection device. Background Technology

[0002] In recent years, 3D printing technology (additive manufacturing) has revolutionized traditional processing methods through its layered, stacked digital manufacturing model. In the medical field, photopolymerization technologies (such as SLA / DLP) have become the mainstream choice for dental restorations (crowns, implant guides, etc.) due to their high resolution (up to 10μm~25μm) and the maturity of biocompatible resin materials. As 3D printing technology penetrates into medical settings, chairside dental printing equipment needs to meet the immediate demands of integrated diagnosis and treatment, accelerating its iteration towards miniaturization, precision, and high integration. However, existing technologies still face significant bottlenecks:

[0003] Low equipment integration: Mainstream DLP optical engines need to maintain a long optical path (typically 60mm~80mm) to ensure light uniformity and energy density, resulting in a large optical engine module (200×150×100mm). The overall size of the machine is generally >0.5m³, requiring a separate operating table. It also has insufficient compatibility with dental treatment chairs (clinical space utilization rate <42%).

[0004] Poor environmental stability: The aluminum alloy optical engine frame has a high coefficient of thermal expansion (23×10⁻). 6 / ℃), a temperature fluctuation of 10℃ in the examination room can cause optical path deviation, resulting in a printing layer thickness deviation of more than ±8μm, which affects the edge fit of the restoration (the pass rate of the <80μm standard is only 68%).

[0005] The contradiction between material performance and efficiency: High-precision printing relies on low-viscosity resin (<300cP), but clinical applications require both strength (flexural modulus >2000MPa) and efficiency (single crown printing time <20min), posing stringent challenges to optomechanical energy density (≥8mW / cm²) and thermal management.

[0006] 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

[0007] The purpose of this application is to provide a new technical solution for 3D printing optical engine lenses and projection equipment.

[0008] In a first aspect, this application provides a 3D printing optical engine lens, the 3D printing optical engine lens comprising a first lens group, an aperture stop, and a second lens group arranged sequentially from the object plane to the image plane, wherein:

[0009] The first lens group includes a first lens and a second lens arranged at intervals; the first lens is a positive lens, and the second lens is a negative lens;

[0010] The second lens group includes a third lens, a fourth lens, a fifth lens, and a sixth lens arranged independently along the principal optical axis, and the optical center of the second lens is located on the principal optical axis;

[0011] The 3D printing optical engine lens also includes a reversing optical element, which is disposed at at least one of the following locations:

[0012] Between the first lens and the second lens;

[0013] The object plane side of the first lens;

[0014] The folding optical element is configured to fold the optical path to form a folded optical path. The 3D printing optical engine lens satisfies the following: the total optical length L ≤ 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.

[0015] Optionally, the total focal length F of the 3D printing optical engine lens satisfies: 8mm≤F≤9mm.

[0016] Optionally, the air gap A between the first lens and the second lens is: 12mm≤A≤15mm.

[0017] Optionally, the optical center of the first lens is located on the principal optical axis; or,

[0018] The optical center of the first lens is located on the first optical axis, and the first optical axis is perpendicular to the principal optical axis.

[0019] Optionally, the deflecting optical element is a mirror or a prism.

[0020] Optionally, the bending optical element includes:

[0021] A first deflection element is disposed on the object side of the first lens to deflect the light beam by 90°.

[0022] The second deflection element is disposed between the first lens and the second lens, and is used to enable the light beam to be deflected 90° again so as to return to the direction of the main optical axis for transmission.

[0023] The optical path of the 3D printing optical engine lens is configured as follows:

[0024] A U-shaped folded optical path, wherein the image plane and the object plane are located on the same side and the principal optical axis is perpendicular to the object plane; or

[0025] Z-shaped folded optical path, in which the image plane and object plane are located on different sides and the principal optical axis is perpendicular to the object plane.

[0026] Optionally, both the first and second turning elements are mirrors or prisms.

[0027] Optionally, only one of the deflecting optical elements is provided, which is used to deflect the light beam 90° back to the direction of the principal optical axis for transmission;

[0028] The folding optical element is disposed 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 engine lens is configured as an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90° and the principal optical axis is parallel to the object plane.

[0029] Optionally, the refractive index nd1 of the first lens is 1.7~1.75;

[0030] The refractive index nd2 of the second lens is 1.5~1.53.

[0031] Optionally, the third lens is a positive lens with a temperature refractive index coefficient dn3 / dt3 of 3.5 × 10⁻⁶. -6 / ℃~6.5×10 -6 / ℃;

[0032] The fourth lens is a negative lens, and its temperature refractive index coefficient dn3 / dt4 is -6×10⁻⁶. -6 / ℃~-7×10 -6 / ℃.

[0033] Optionally, both the fifth and sixth lenses are positive lenses.

[0034] Optionally, the refractive index of the third lens, the fifth lens, and the sixth lens is 1.7 to 1.75, and the refractive index of the fourth lens is 1.487 to 1.53;

[0035] The difference between the Abbe number of any one of the third, fifth, and sixth lenses and the Abbe number of the fourth lens is greater than 25.

[0036] Optionally, the first to the sixth lens are all independently assembled glass lenses.

[0037] Secondly, this application provides a projection device, the projection device comprising:

[0038] The 3D printing optical engine lens mentioned in the first aspect; and

[0039] An equivalent prism or prism, a galvanometer, and an image source are arranged sequentially along the backlight path.

[0040] The beneficial effects of this application are as follows:

[0041] The 3D printing optical engine lens solution provided in this application embodiment configures a combination of positive and negative lenses with negative distortion compensation function in the first lens group: the first lens is a positive lens, and its second surface is specially designed to introduce negative distortion. Working in synergy with the second lens, which acts as a negative lens, it can effectively counteract lens distortion generated during short object distance (<50mm) imaging, ensuring a significant reduction in the distortion rate across the entire field of view, fully meeting the high-precision printing requirements of dental restorations. Simultaneously, this 3D printing optical engine lens incorporates a folded optical path by introducing a bending optical element. This design compresses the total optical length of the optical engine lens along the principal optical axis to within 54mm and controls the air gap between the first and second lenses to be 30%~40%, which significantly reduces assembly sensitivity (tolerance relaxed to ±80μm). The optical solution provided in this application embodiment not only achieves a high degree of integration of the 3D printing optical engine lens (its volume can be reduced to, for example, 60×60×40mm), but also significantly improves imaging accuracy, making it particularly suitable for the stringent requirements of miniaturization and high precision in dental chairside 3D printing equipment.

[0042] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0043] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0044] Figure 1 This is one of the structural schematic diagrams of a 3D printing optical engine lens provided in an embodiment of this application;

[0045] Figure 2 This is a second schematic diagram of the structure of a 3D printing optical engine lens provided in an embodiment of this application;

[0046] Figure 3 This is the third schematic diagram of the structure of the 3D printing optical engine lens provided in the embodiments of this application;

[0047] Figure 4 This is the fourth schematic diagram of the structure of the 3D printing optical engine lens provided in the embodiments of this application;

[0048] Figure 5 Fifth schematic diagram of the structure of the 3D printing optical engine lens provided in the embodiments of this application;

[0049] Figure 6 This is a projection distortion diagram of the 3D printing optical engine lens provided in Embodiment 1 of this application;

[0050] Figure 7 The MTF diagram of the 3D printing optical engine lens provided in Embodiment 1 of this application;

[0051] Figure 8 Field curvature and distortion diagram of the 3D printing optical engine lens provided in Embodiment 1 of this application;

[0052] Figure 9 This is a projection distortion diagram of the 3D printing optical engine lens provided in Embodiment 2 of this application;

[0053] Figure 10 The MTF diagram of the 3D printing optical engine lens provided in Embodiment 2 of this application;

[0054] Figure 11 The field curvature and distortion diagram of the 3D printing optical engine lens provided in Embodiment 2 of this application.

[0055] Explanation of reference numerals in the attached figures:

[0056] 1. First lens group; G1. First lens; S1. First surface; S2. Second surface; G2. Second lens; S3. Third surface; S4. Fourth surface;

[0057] 2. Second lens group; G3, third lens; G4, fourth lens; G5, fifth lens; G6, sixth lens;

[0058] 3. Aperture;

[0059] 4. Shifting optical elements; 41. Reflector; 42. Prism;

[0060] 5. Equivalent prism; 6. Pleistosity prism; 7. Galvanometer; 8. Image source. Detailed Implementation

[0061] 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 arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0062] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0063] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0064] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0065] 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.

[0066] The 3D printing optical engine lens and projection device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0067] According to one embodiment of this application, a 3D printed optical engine lens is provided, see [link]. Figure 1 and 5 The 3D printing optical engine lens includes a first lens group 1, an aperture stop 3, and a second lens group 2 arranged sequentially from the object plane to the image plane. Specifically: the first lens group 1 includes a first lens G1 and a second lens G2 spaced apart; the first lens G1 is a positive lens, and its second surface S2 near the aperture stop 3 is configured to produce negative distortion to compensate for the distortion generated by the entire 3D printing optical engine lens during short-distance projection; the second lens G2 is a negative lens. The second lens group 2 includes a third lens G3, a fourth lens G4, a fifth lens G5, and a sixth lens G6 arranged independently along the principal optical axis, and the optical center of the second lens G2 is located on the principal optical axis. The 3D printing optical engine lens further includes a reversing optical element 4, which is disposed at least at one of the following locations: between the first lens G1 and the second lens G2, and on the object side of the first lens G1; the reversing optical element 4 is configured to reversing the optical path to form a folded optical path, and the 3D printing optical engine lens satisfies the following: the total optical length L ≤ 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.

[0068] The 3D printing optical engine lens provided in this application, with its compact overall optical length (L≤54mm) and high-precision imaging performance, exhibits significant advantages in applications such as dental chairside 3D printing equipment. Therefore, the 3D printing optical engine lens provided in this application, through its highly integrated design, is specifically designed to meet the stringent requirements of space efficiency and imaging accuracy in integrated diagnostic and therapeutic scenarios, and is particularly suitable for space-constrained clinical environments such as dental chairside cabinets.

[0069] By introducing one or two bending optical elements 4 into the optical path of the 3D printed optical engine lens (the total optical length of the entire 3D optical engine lens along the main optical axis is ≤54mm, and the volume of the optical engine lens is 60×60×40mm), and in conjunction with the negative distortion compensation technology in the optical path (distortion rate <0.5% across the entire field of view), the 3D printed optical engine lens provided in this application embodiment can be seamlessly embedded in space-constrained devices such as dental chair side cabinets, and can meet the accuracy requirements of ±15μm for dental restorations (such as crowns and implant guides).

[0070] The technical characteristics of the 3D printing optical engine lens provided in this application embodiment also give it the potential for cross-domain applications. For example, the application fields of the 3D printing optical engine lens include, but are not limited to, diverse fields such as micro-nano manufacturing and precision processing, biomedical engineering, and portable 3D printing equipment.

[0071] The main components of the 3D printing optical engine lens provided in the embodiments of this application are described in detail below.

[0072] The 3D printing optical engine lens provided in this application embodiment is described in [reference]. Figures 1 to 5 Its 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).

[0073] The first lens G1 is designed as a positive lens, and its optical surface includes a first surface S1 far from the aperture stop 3 and a second surface S2 close to the aperture stop 3. The second surface S2 is designed to have negative distortion generation capability. Its purpose is to effectively offset the distortion of the entire 3D printing optical engine lens caused by the excessively close projection distance during short object distance (<50mm) imaging after multiple changes in object distance during the 3D printing process by introducing a large TRANSVER negative distortion. This ensures that the distortion rate of the 3D printing optical engine lens provided in this application is <0.5% across the entire field of view, thereby meeting the ±15μm accuracy requirement for dental restorations (such as crowns and implant guides).

[0074] In addition, the spherical aberration, coma, field curvature and astigmatism coefficients of the first lens G1 are all controlled within a small range, and its tilt or eccentricity has a significant reduction in the impact on the overall optical-mechanical lens image quality, providing a higher tolerance for subsequent assembly.

[0075] The second lens G2 is designed as a negative lens, which, together with the first lens G1 (a positive lens), forms a positive-negative lens combination optical structure. This combination 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 (air gap A accounts for 30%~40% of the total optical length along the principal optical axis of the lens):

[0076] (1) Spatial optimization: for subsequent optical path turning (such as U-shaped, Z-shaped, L-shaped folding, see Figures 1 to 5 It provides ample layout space to support the miniaturization design of 3D printed optical engine lenses;

[0077] (2) Reduced 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 ±80μm (5 to 8 times more relaxed 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 reliance on manual adjustment experience, and reduces manufacturing costs.

[0078] In summary, in the first lens group 1, the positive and negative optical powers of the first lens G1 and the second lens G2 are matched. Combined with negative distortion compensation, aberration correction, and reduced assembly sensitivity, this overcomes the contradiction between printing accuracy and product size in traditional printing optical engine lenses. In particular, this application provides a reliable optical solution for high-precision applications such as dental chairside 3D printing equipment.

[0079] The 3D printing optical engine lens provided in this application embodiment is described in [reference]. Figures 1 to 5 Its optical structure also includes an aperture stop 3, which is located between the first mirror group 1 and the second mirror group 2. As a key beam control element, the aperture stop 3 mainly performs the following functions:

[0080] Beam aperture control: By limiting the effective diameter of the incident beam, aperture 3 can effectively suppress interference from non-imaging light rays and prevent stray light from entering the 3D printing optical engine lens, thereby significantly improving the contrast of the displayed image and ensuring the clarity of the printed structure edges.

[0081] Aberration correction synergistic optimization: The aperture stop 3 and the first lens group 1 (including the first lens G1 and the second lens G2) form an optical synergistic system. The position of the aperture stop 3 is optimized by 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 in the entire field of view.

[0082] Achieving a 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 >50%, which allows the volume of the entire 3D printing optical engine lens to be reduced to 60×60×40mm, thus meeting the embedded installation requirements of dental chair side cabinets.

[0083] It can be seen that by combining the aperture 3 with the first mirror group 1, a balance is achieved between controlling stray light, correcting aberrations, and realizing miniaturization.

[0084] The optical structure of the 3D printing optical engine lens provided in this embodiment is described in [reference needed]. Figures 1 to 5It also includes a second lens group 2 located on the image plane side, which is mainly composed of third lens G3 to sixth lens G6 arranged independently along the principal optical axis. This second lens group 2, acting as a converging ray group, forms a dispersion compensation structure by differentiating the refractive indices of each lens (e.g., a combination of a negative lens with a refractive index of 1.487~1.53 and a positive lens with a refractive index of 1.7~1.75) and Abbe numbers (the difference in Abbe numbers between positive and negative lenses > 25). This optical design can systematically correct the residual spherical aberration (wavelength aberration < 0.05λ) and field curvature (sagittal difference < 0.02mm) of the optical engine lens, ensuring consistent image sharpness across the entire field of view. This is particularly beneficial for the precise shaping of the edge contours of dental restorations.

[0085] The collaborative optimization mechanism between the aperture 3 and the first lens group 1 and the second lens group 2 is as follows:

[0086] The aperture 3, by controlling the effective aperture of the incident beam, synergistically optimizes the negative distortion compensation of the first lens group 1 (transversor negative distortion of the second surface S2 of the first lens G1) and the aberration correction of the second lens group 2. This synergistic optimization design can improve the marginal fit qualification rate of dental restorations from 68% to 92% with an accuracy of ±15μm, while ensuring that the MTF value of the 3D printing optical engine lens at a spatial frequency of 93lp / mm is >0.7 (average value across the entire field of view). See [link to relevant documentation]. 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, enabling cross-domain precision manufacturing applications.

[0087] The 3D printing optical engine lens provided in this application embodiment is described in [reference]. Figures 1 to 5 Furthermore, a special deflection optical element 4 is introduced into its optical structure. This deflection optical element 4 (reflector 41 or prism 42) allows the original direct-transmission optical path to form a U-shaped / Z-shaped / L-shaped deflection, thereby achieving dimensional compression of the optical path along the principal optical axis. For example, this design can reduce the traditional 60mm~80mm principal optical axis length to ≤53.8mm (including DMD tilt compensation space), with an axial compression rate (here, axial refers to the principal optical axis direction) exceeding 51.8%, thus optimizing the overall machine size to a compact 60×60×40mm. This design allows the 3D-printed optical engine lens to be seamlessly embedded in the dental chair side cabinet (standard accommodation space ≥100×70×50mm), achieving a space adaptability rate of over 97%, solving the problem of insufficient physical compatibility of equipment in clinical treatment environments.

[0088] In this embodiment, the transition optical element 4 can achieve spatial compression, for example, through a two-stage optical path transition. See [link to relevant documentation]. Figures 1 to 3 :

[0089] First-stage deflection: A high-reflectivity deflection optical element 4 (e.g., reflectivity > 98% @ 405nm) at a 45° angle can be placed behind the second surface S2 of the first lens G1. This can be used to deflect the beam 90° to the lateral optical path, which breaks the dependence of the traditional straight-line optical path on axial space.

[0090] The second stage of folding: A second high-reflectivity deflecting optical element 4 is placed before the front surface of the second lens G2, i.e., the third surface S3. Its purpose is to deflect the beam again by 90°, causing the beam to return to the principal optical axis direction and complete the optical path folding, such as Z-shaped or U-shaped folding, as detailed in the relevant sections. Figures 1 to 3 .in, Figure 1 and Figure 3 This shows a U-shaped folded optical path. Figure 2 This shows a Z-shaped folded optical path.

[0091] The 3D printing optical engine lens provided in this application embodiment configures a combination of positive and negative lenses with negative distortion compensation function 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. Working in synergy with the second lens G2, which is a negative lens, it can effectively counteract lens distortion generated during short object distance (<50mm) imaging, ensuring a significant reduction in the distortion rate across the entire field of view, fully meeting the high-precision printing requirements of dental restorations. Simultaneously, the 3D printing optical engine lens incorporates a folded optical path by introducing a folding optical element 4. This design can compress the total optical length of the 3D printing optical engine lens in the principal optical axis direction to within 54mm, and control the air gap A between the first lens G1 and the second lens G2 to account for 30%~40%, which can significantly reduce assembly sensitivity (tolerance relaxed to ±80μm).

[0092] The optical solution provided in this application not only achieves a high degree of integration of the 3D printing optical engine lens, reducing its size to, for example, 60×60×40mm, but also significantly improves imaging accuracy. It is particularly suitable for the stringent requirements of miniaturization and high precision in dental chairside 3D printing equipment.

[0093] In some examples of this application, the total focal length F of the 3D printing optical engine lens satisfies: 8mm≤F≤9mm.

[0094] In the example of this application, the total focal length range of the 3D printing optical engine 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), achieving a TRO (projection ratio) of 1.3 to 1.6 for the projection optics system. This ratio ensures that the beam can still completely cover the effective imaging area of ​​the DMD chip even at short object distances (<50mm), avoiding edge image quality degradation (such as field curvature error >30μm) caused by beam divergence in traditional long focal length (focal length >12mm) schemes, or the decrease in printing efficiency caused by insufficient light energy density in short focal length schemes.

[0095] Within the 8mm~9mm focal length range, a large TRANSVER negative distortion design is introduced through the second surface S2 of the first lens G1, which effectively counteracts nonlinear distortion during short object distance imaging, resulting in a distortion rate of <0.5% (F-Theta nonlinear error <0.05%) across the entire field of view. Compared to traditional long focal length (focal length >12mm) solutions, this design can reduce the field curvature error at the edge of the field of view from >30μm to <8μm, thereby significantly improving the printing success rate of complex structures such as micro-mechanical parts.

[0096] This compact focal length design provides key parameters for optical path deflection in optical engine lenses, specifically:

[0097] When the total focal length F of the 3D printing optical engine lens is 8mm~9mm, combined with a U-shaped or Z-shaped folded optical path design, see [reference needed]. Figures 1 to 3 This technology can compress the original 103.8mm optical path to approximately 50mm, achieving an axial compression rate of 51.8%, and reducing the overall size of the device to 60×60×40mm. This size allows the 3D-printed optical engine lens to be directly embedded in the side cabinet of the dental treatment chair (standard capacity ≥100×70×50mm), solving the problem of insufficient physical compatibility of equipment in the treatment environment.

[0098] With a total focal length design of 8mm~9mm, by increasing the air gap A between the first lens G1 and the second lens G2 (accounting for 30%~40% of the total optical length L), assembly sensitivity can be significantly reduced. For example, the assembly tolerance is relaxed from ±10μm in the traditional scheme to ±80μm. Simultaneously, optical path optimization maintains the optical-mechanical lens MTF@93lp / mm>0.7 (average across the entire field of view), see [reference needed]. Figure 7 .

[0099] In some examples of this application, the air gap A between the first lens G1 and the second lens G2 is: 12mm≤A≤15mm.

[0100] 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 12mm to 15mm, combined with the folded optical path design (introducing the folded optical element 4 to form a folded optical path), the synergistic optimization of optical performance and assembly compatibility is achieved.

[0101] In this embodiment, the air gap A is relatively large. This design can reduce the sensitivity of the 3D printing optical engine lens to the eccentricity and tilt of the internal lenses. In traditional compact optical paths, the spacing between lenses needs to be controlled within ±10μm, otherwise the image quality (such as MTF value) will degrade.

[0102] This application utilizes a large air gap A design, such as 12mm~15mm, to widen the assembly tolerance to ±80μm, which helps reduce manufacturing costs and improve yield. Simultaneously, optical path optimization maintains the optical engine lens MTF@93lp / mm>0.7 (average across the entire field of view), see [link to relevant documentation]. Figure 7 .

[0103] See some examples in this application. Figure 5 The optical center of the first lens G1 is located on the principal optical axis; or, see [link to relevant documentation]. 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 principal optical axis.

[0104] See 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. At this time, 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.

[0105] See Figure 5 The first lens G1 and the second lens G2 are spaced apart along the same optical axis, meaning that 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 two adjacent surfaces of the two lenses, namely the second surface S2 and the third surface S3.

[0106] See some examples in this application. Figures 1 to 5 The deflecting optical element 4 is a mirror 41 or a prism 42.

[0107] The reflector 41 can achieve directional deflection of the light beam, for example, through a high-reflectivity coating (reflectivity > 98% @ 405nm). For example, in the optical path design provided in this application, the reflector 41 can deflect the incident light beam by 90° (such as a first-stage deflection) or deflect it in the opposite direction by 90° (such as a second-stage reflection), thereby compressing the axial space (along the principal optical axis) of the 3D printing optical engine lens.

[0108] The deflecting optical element 4 is, for example, a plane mirror tilted at 45°, and its surface may be coated with a high reflectivity coating.

[0109] Of course, the prism 42 can also be used to deflect the light beam.

[0110] The prism 42 is, for example, a right-angled triangular prism, whose reflecting surface is an inclined plane.

[0111] By designing the beam deflection of the reflector 41 or prism 42, the size of the 3D printing optical engine lens provided in this application embodiment can be reduced from the traditional 200×150×100mm to 60×60×40mm, making it suitable for dental treatment chair side cabinets (standard capacity ≥100×70×50mm).

[0112] See some examples in this application. Figures 1 to 3 The deflecting optical element 4 includes two deflecting elements: a first deflecting element and a second deflecting element. The first deflecting element is disposed on the object plane side of the first lens G1 to deflect the light beam by 90°. The second deflecting element is disposed between the first lens G1 and the second lens G2 to deflect the light beam again by 90°, allowing it to return to the principal optical axis direction for transmission. The optical path of the 3D printing optical engine lens is configured as either a U-shaped folded optical path or a Z-shaped folded optical path. See also... 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. See also Figure 2 In the Z-shaped folded optical path, the image plane and the object plane are located on different sides and the principal optical axis is perpendicular to the object plane.

[0113] In the example provided in this application, see [link to example]. Figures 1 to 3 By introducing dual-folding elements, namely the first folding element and the second folding element, into the 3D printed optical engine lens, a U-shaped or Z-shaped folded optical path design can be formed, realizing the compactness of the 3D printed optical engine lens structure and the high-precision synergistic optimization of optical performance.

[0114] Specifically, see Figures 1 to 3The first deflection element is disposed on the object plane side of the first lens G1, and its core function is to deflect the incident beam by 90° and guide it laterally into the subsequent optical path. The second deflection element is located between the first lens G1 and the second lens G2, and deflects the beam by another 90° to return it to the principal optical axis direction, forming a closed optical path. The dual deflection elements achieve a 180° deflection of the beam through two orthogonal deflections, compressing the axial (principal optical axis) space.

[0115] For example, in a U-shaped folded optical path, the first deflection element converts the beam from longitudinal to transverse, and the second deflection element converts it back to longitudinal, forming a U-shaped path. See [link to relevant documentation]. Figure 1 and Figure 3 .

[0116] Please continue reading Figure 1 and Figure 3 The U-shaped folded optical path design has the following features:

[0117] (1) The structure is configured such that the image plane is on the same side as the object plane and the principal optical axis is perpendicular to the object plane.

[0118] (2) The optical path is as follows: the beam is deflected by the first deflection element by 90° and then transmitted laterally. After passing through the first lens G1 and the second lens G2, it is deflected by the second deflection element by 90° and then returns to the principal optical axis.

[0119] With the U-shaped folded optical path design, the total length from the object plane to the image plane is compressed from 103.8 mm to 50 mm (including the DMD tilt compensation space), with a compression rate of 51.8%.

[0120] For example, in a Z-shaped folded optical path, the first deflection element converts the beam from longitudinal to transverse, and the second deflection element converts it back to longitudinal. Because the object plane is positioned on different sides of the image plane, a "Z"-shaped path is formed. (See [link to relevant documentation]). Figure 2 .

[0121] Please continue reading Figure 1 and Figure 3 The U-shaped folded optical path design has the following features:

[0122] (1) The structure is configured such that the image plane and the object plane are located on different sides, and the principal optical axis is perpendicular to the object plane.

[0123] (2) The optical path is as follows: the beam is deflected by the first deflection element by 90° and then transmitted laterally. After passing through the first lens G1 and the second lens G2, it is deflected by the second deflection element by 90° and then transmitted along the principal optical axis to the image plane on the opposite side.

[0124] It should be noted that, through the Z-shaped bend, the length of the 3D optical engine lens provided in this application can also be further compressed.

[0125] See some examples in this application. Figures 1 to 3 Both the first and second turning elements are either mirrors 41 or prisms 42.

[0126] In one example, see Figure 1 The deflecting optical element 4 includes two deflecting elements: a first deflecting element and a second deflecting element. The first deflecting element is disposed on the object plane side of the first lens G1 to deflect the light beam by 90°. The second deflecting element is disposed between the first lens G1 and the second lens G2 to deflect the light beam again by 90° so that it can return to the direction of the principal optical axis for transmission. Both the first deflecting element and the second deflecting element are reflectors 41. The optical path of the 3D printing optical engine lens is configured as a U-shaped folded optical path, wherein the image plane and the object plane are located on the same side and the principal optical axis is perpendicular to the object plane.

[0127] In one example, see Figure 2 The deflecting optical element 4 includes two deflecting elements: a first deflecting element and a second deflecting element. The first deflecting element is disposed on the object plane side of the first lens G1 to deflect the light beam by 90°. The second deflecting element is disposed between the first lens G1 and the second lens G2 to deflect the light beam again by 90° so that it can return to the direction of the principal optical axis for transmission. Both the first deflecting element and the second deflecting element are prisms 42. The optical path of the 3D printing optical engine lens is configured as a Z-shaped folded optical path, wherein the image plane and the object plane are disposed on different sides and the principal optical axis is perpendicular to the object plane.

[0128] In one example, see Figure 3 The deflecting optical element 4 includes two deflecting elements: a first deflecting element and a second deflecting element. The first deflecting element is disposed on the object plane side of the first lens G1 to deflect the light beam by 90°. The second deflecting element is disposed between the first lens G1 and the second lens G2 to deflect the light beam again by 90° so that it can return to the direction of the principal optical axis for transmission. Both the first deflecting element and the second deflecting element are prisms 42. The optical path of the 3D printing optical engine lens is configured as a U-shaped folded optical path, wherein the image plane and the object plane are located on the same side and the principal optical axis is perpendicular to the object plane.

[0129] See some examples in this application. Figure 4 and Figure 5The deflecting optical element 4 is provided only once, and is used to deflect the light beam by 90° back to the direction of the principal optical axis for transmission; the deflecting optical element 4 is provided 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 engine lens is configured as an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90° and the principal optical axis is parallel to the object plane.

[0130] This application, through the introduction of a single-folding element (mirror 41 or prism 42) into the 3D printed optical engine lens, achieves further compactness and optimization of optical performance of the 3D printed optical engine lens. (See also...) Figure 4 and Figure 5 .

[0131] 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), which can be disposed on the object plane 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 redirect the light beam from the longitudinal principal axis to lateral transmission through a single 90° deflection, and then converge it to the image plane via the subsequent second mirror group 2, forming an "L"-shaped light path. See [reference needed]. Figure 4 and Figure 5 .

[0132] In one example, see Figure 4 The deflecting optical element 4 is provided only once and is a reflector 41, used to deflect the light beam 90° back to the direction of the principal optical axis for transmission. The deflecting optical element 4 is provided between the first lens G1 and the second lens G2. The optical path of the 3D printing optical engine lens is configured as an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90° and the principal optical axis is parallel to the object plane.

[0133] In one example, see Figure 5 The deflecting optical element 4 is provided only once and is a prism 42, used to deflect the light beam 90° back to the direction of the principal optical axis for transmission. The deflecting optical element 4 is provided on the object plane side of the first lens G1. The optical path of the 3D printing optical engine lens is configured as an L-shaped folded optical path, wherein the image plane and the object plane are distributed at 90° and the principal optical axis is parallel to the object plane.

[0134] Through the L-shaped bend, the length of the 3D optical engine lens provided in this application is further compressed.

[0135] In some examples of this application, the refractive index nd1 of the first lens G1 is 1.7~1.75.

[0136] The refractive index nd2 of the second lens G2 is 1.5~1.53.

[0137] The first lens G1 is a positive lens with a high refractive index nd1 = 1.7~1.75. The first lens G1 is, for example, heavy flint glass, such as H-ZBAF21 or H-LAF4GT. Its high refractive index can enhance the light-gathering ability, and at the same time, it introduces negative distortion (TRANSVER distortion coefficient -0.8%~-1.2%) through its second surface S2 to offset the imaging distortion at short object distances (<50mm).

[0138] The second lens G2 is a negative lens with a low refractive index nd2 = 1.5~1.53. The second lens G2 is made of, for example, light flint glass, such as H-FK61 or H-QK3L. Its low refractive index reduces the angle of light refraction and forms a positive and negative lens combination with the first lens G1, which can be used to balance the aberrations of the entire optical and mechanical lens.

[0139] Specifically, the first lens G1 and the second lens G2 form a positive and 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 12mm~15mm (accounting for 30%~40% of the total system length). The large air gap A provides space for the subsequent reversing optical path and also makes the spacing between the first lens G1 and the second lens G2 insensitive. The first lens G1 has very small coefficients of spherical aberration, coma, field curvature, and astigmatism, and its tilt and eccentricity have little impact on the image quality of the entire 3D printing optical engine lens, meeting the assembly tolerance requirements of the reversing optical element 4 and the first lens G1. A large TRANSVER negative distortion is introduced through the second surface S2 of the first lens G1 to offset the short object distance imaging distortion.

[0140] See some examples in this application. Figures 1 to 5 The third lens G3 is a positive lens with a 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 / ℃.

[0141] 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 two work together to achieve focal plane stability of the 3D printing optical engine lens in the temperature range of -20℃ to 80℃ (its offset is <±3μm).

[0142] The third lens G3 is a positive lens, whose positive temperature refractive index (dn / dt) increases significantly with increasing temperature, enhancing light converging ability and compensating for the thermal expansion (CTE = 2.35 × 10⁻⁻¹) of the aluminum alloy lens barrel (used to house the lenses). 6 / ℃).

[0143] The fourth lens G4 is a negative lens, whose negative temperature refractive index coefficient (dn4 / dt4) decreases the light refraction angle as the temperature increases. It forms an inverse compensation pair with the third lens G3, thereby counteracting the linear expansion of the aluminum alloy frame.

[0144] When the ambient temperature rises: the dn / dt of the third lens G3 shortens the focal length, while the dn / dt of the fourth lens G4 lengthens the focal length. The combined change in focal length offsets the expansion of the lens barrel. When the ambient temperature decreases: the reverse process applies, ensuring that the focal plane offset is <±3μm.

[0145] See some examples in this application. Figures 1 to 5 Both the fifth lens G5 and the sixth lens G6 are positive lenses.

[0146] In the optical path of the 3D printing optical engine lens in this embodiment, the fifth lens G5 and the sixth lens G6 are located at the end of the optical path (close to the image plane) in sequence. Through the convergence effect, the total length from the object plane to the image plane of the entire projection device is compressed from 103.8mm to 53.8mm (including the DMD tilt compensation space), and the axial compression rate can reach 51.8%.

[0147] See Figure 7 According to MTF performance testing: at a spatial frequency of 93 lp / mm, the average MTF value of the 3D printing optical engine lens provided in this application embodiment is >0.7, which is 40% higher than that of the traditional design (MTF <0.5), meeting the requirements of ISO 12836 standard for the accuracy of dental restorations (±15μm).

[0148] In some examples of this 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; 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 >25.

[0149] This 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; and setting the refractive index of the fourth lens G4 to 1.487~1.53 and the Abbe number vd≈65. By utilizing the characteristic that the difference in Abbe number between lenses is > 25, this application achieves correction of spherical aberration (residual wave aberration < 0.05λ) and field curvature (maximum sag difference < 0.02mm).

[0150] This combination of Abbe number difference > 25 results in smaller axial and lateral chromatic aberrations in the optical lens, which can meet the color reproduction requirements of dental restorations (biocompatible resin materials require precise control of curing wavelength).

[0151] See some examples in this application. Figures 1 to 5 The first lens G1 to the sixth lens G6 are all independently assembled glass lenses.

[0152] This application solves the problems of aging risk, high assembly sensitivity and light transmittance decay of traditional cemented lenses in 3D printing optical engines by designing the first lens G1 to the sixth lens G6 as independently assembled all-glass lenses, combined with a non-cemented structure and material optimization.

[0153] Traditional cemented lenses typically use UV adhesive for bonding, but the UV light introduced during 3D printing accelerates the aging of the adhesive layer between lenses. This application eliminates this aging risk through a design that uses independently assembled lenses made entirely of glass. This adhesive-free structure effectively avoids UV adhesive delamination and yellowing, achieving a light transmittance >99.2%@405nm.

[0154] According to another embodiment of this application, a projection device is provided, see [link to relevant documentation]. Figures 1 to 5 The projection device includes: a 3D printing optical engine lens as described above, and an equivalent prism 5 or prism 6, a galvanometer 7, and an image source 8 arranged sequentially along the backlight path.

[0155] The image source 8 is used to generate projection light, which is then projected onto the 3D printing optical engine lens via the galvanometer 7, the equivalent bending prism 5, or the bending prism 6. The projection light then forms a projected image on the projection screen.

[0156] The galvanometer 7, equivalent bending prism 5, bending prism 6, and image source 8 can all be based on existing technologies. Their structure and working principle will not be described in detail here.

[0157] The projection device provided in this application uses the 3D printed optical engine 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 engine lens can reach 1.3 to 1.6, with small optical distortion, good imaging, and high projection quality.

[0158] The specific implementation of the projection device in this application can refer to the various embodiments of the 3D printing optical engine lens described above. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0159] Please refer to the optical structure of the 3D printing optical engine lens provided in this application embodiment. Figures 1 to 5 As shown, the 3D printing optical engine lens can be Figures 1 to 5 Any of the optical architectures shown herein. The 3D printed optical engine lens is described in detail below through Examples 1 and 2.

[0160] Example 1

[0161] The optical frame of the 3D printed optical engine lens provided in this application can be Figures 1 to 5 Any one of them, and the optical parameters of the 3D printed optical engine lens are designed as shown in Table 1 and Table 2, where Table 2 is the primary Seid coefficient of the optical surface of each lens shown in Table 1.

[0162] Combining the optical parameters shown in Tables 1 and 2, Figures 6 to 8 The optical performance diagram of the 3D printing optical engine lens provided in Embodiment 1 is shown. Specifically, see... Figure 7 , Figure 7 The MTF value shown is: MTF@93lp / mm > 0.7 (average value across the entire field of view). See also 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.

[0163] Please refer to Tables 1 and 2. The integrated dimensions of the 3D printed optical engine lens provided in this embodiment 1 are only 60mm × 60mm × 40mm (L × W × H). This size allows the 3D printed optical engine lens to be embedded in the dental chair side cabinet (the dental chair side cabinet has a capacity of ≥100mm × 70mm × 50mm).

[0164] It should be noted that Table 2 is used to explain why a large air gap A provides sufficient space for the subsequent reversing optical path, while also making the gap between the first lens G1 and the second lens G2 insensitive. Specifically, the first lens G1 has very small coefficients for spherical aberration, coma, field curvature, and astigmatism, and its tilt and eccentricity have minimal impact on the image quality of the entire 3D printing optical engine lens, thus meeting the tolerance requirements for the reversing optical element 4 and the first lens G1. A large TRANSVER negative distortion is introduced through the second surface S2 of the first lens G1 to offset short object distance imaging distortion.

[0165] Table 1

[0166]

[0167] Table 2

[0168]

[0169] Example 2

[0170] The optical frame of the 3D printed optical engine lens provided in this application can be Figures 1 to 5 Any one of them, and the optical parameters of the 3D printed optical engine lens are designed as shown in Table 3 and Table 4, where Table 4 is the primary Seid coefficient of the optical surface of each lens shown in Table 3.

[0171] Combining the optical parameters shown in Tables 3 and 4, Figures 9 to 11 The optical performance diagram of the 3D printing optical engine lens provided in Embodiment 2 is shown. Specifically, see... Figure 10 , Figure 10 The MTF value shown is: MTF@93lp / mm > 0.75 (average value across the entire field of view). See also 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.

[0172] Referring to Tables 3 and 4, the integrated dimensions of the 3D printing optical engine lens provided in this embodiment 2 are only 60mm × 60mm × 40mm (L × W × H). This size allows the 3D printing optical engine lens to be embedded in the dental chair side cabinet (the dental chair side cabinet has a capacity of ≥100mm × 70mm × 50mm).

[0173] It should be noted that Table 4 is used to explain that the large air gap A provides sufficient space for the subsequent reversing optical path, while also making the gap between the first lens G1 and the second lens G2 insensitive. Specifically, the spherical aberration, coma, field curvature, and astigmatic aberration coefficients of the first lens G1 are very small, and its tilt and eccentricity have little impact on the image quality of the entire 3D printing optical engine lens, which can meet the assembly tolerance requirements of the reversing optical element 4 and the first lens G1. A large TRANSVER negative distortion is introduced through the second surface S2 of the first lens G1 to offset the short object distance imaging distortion.

[0174] Table 3

[0175]

[0176] Table 4

[0177]

[0178] The above embodiments mainly describe 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. For the sake of brevity, they will not be elaborated here.

[0179] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A 3D printed optical engine lens, characterized in that, It includes a first mirror group (1), an aperture stop (3), and a second mirror group (2) arranged sequentially from the object plane to the image plane, wherein: The first lens group (1) consists of a first lens (G1) and a second lens (G2) 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) consists of a third lens (G3), a fourth lens (G4), a fifth lens (G5), and a sixth lens (G6) arranged independently along the principal optical axis, and the optical center of the second lens (G2) is located on the principal optical axis; the third lens (G3) is a positive lens, the fourth lens (G4) is a negative lens, and the fifth lens (G5) and the sixth lens (G6) are all positive lenses; The 3D printing optical engine lens also includes a reversing optical element (4), which is disposed at least at one of the following locations: Between the first lens (G1) and the second lens (G2); The object plane side of the first lens (G1); The folding optical element (4) is configured to fold the optical path to form a folded optical path. The 3D printing optical engine lens satisfies the following: the total optical length L ≤ 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. The air gap A between the first lens (G1) and the second lens (G2) is: 12mm≤A≤15mm.

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

3. The 3D printing optical engine lens according to claim 1, 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 the first optical axis, and the first optical axis is perpendicular to the principal optical axis.

4. The 3D printing optical engine lens according to any one of claims 1-3, characterized in that, The deflecting optical element (4) is a mirror (41) or a prism (42).

5. The 3D printing optical engine lens according to claim 4, characterized in that, The transition optical element (4) includes: The first deflection element is disposed on the object plane side of the first lens (G1) to deflect the beam by 90°; The second deflection element is disposed between the first lens (G1) and the second lens (G2) to enable the light beam to be deflected again by 90° so as to return to the direction of the main optical axis for transmission; The optical path of the 3D printing optical engine lens is configured as follows: A U-shaped folded optical path, wherein the image plane and the object plane are located on the same side and the principal optical axis is perpendicular to the object plane; or Z-shaped folded optical path, in which the image plane and object plane are located on different sides and the principal optical axis is perpendicular to the object plane.

6. The 3D printing optical engine lens according to claim 5, characterized in that, Both the first and second transition elements are either mirrors (41) or prisms (42).

7. The 3D printing optical engine lens according to claim 4, characterized in that, Only one of the aforementioned deflection optical elements (4) is provided, which is used to deflect the beam by 90° back to the direction of the principal optical axis for transmission; The folding optical element (4) is disposed 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 engine lens is configured as an L-shaped folding optical path, wherein the image plane and the object plane are distributed at 90° and the principal optical axis is parallel to the object plane.

8. The 3D printing optical engine lens according to claim 4, 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.

9. The 3D printing optical engine lens according to claim 4, characterized in that, The temperature refractive index coefficient dn3 / dt3 of the third lens (G3) is 3.5 × 10⁻⁶. -6 / ℃~6.5×10 -6 / ℃; The temperature refractive index coefficient dn3 / dt4 of the fourth lens (G4) is -6×10⁻⁶. -6 / ℃~-7×10 -6 / ℃.

10. The 3D printing optical engine lens according to claim 1, characterized in that, The refractive indices of the third lens (G3), the fifth lens (G5), and the sixth lens (G6) are 1.7 to 1.75, and the refractive index of the fourth lens (G4) is 1.487 to 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.

11. The 3D printing optical engine lens according to claim 4, characterized in that, The first lens (G1) to the sixth lens (G6) are all independently assembled glass lenses.

12. A projection device, characterized in that, include: The 3D printing optical engine lens according to any one of claims 1-11; as well as An equivalent prism (5) or prism (6), a galvanometer (7) and an image source (8) are arranged sequentially along the backlight path.

Images