Projection optical system
By using a combination of plastic aspherical lenses and glass spherical lenses in the projection optics system, the problem of unclear images under high brightness and high temperature was solved, achieving low-cost, high-performance, and high-definition projection effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ZHONGSHAN UNITED OPTOELECTRONIC DISPLAY TECHNOLOGY CO LTD
- Filing Date
- 2025-07-15
- Publication Date
- 2026-07-14
AI Technical Summary
Existing projection lenses suffer from performance degradation under high brightness and high temperature conditions, especially resulting in unclear images. Furthermore, high-performance lenses are expensive, while low-cost lenses cannot meet visual perception requirements.
A combination of plastic aspherical lenses and glass spherical lenses is used. The plastic lenses are used to improve aberrations and reduce costs, while the glass lenses are used to resist thermal deformation. By rationally controlling the lens focal length and material combination, high performance and high brightness are ensured.
High performance and high brightness were achieved at low cost, ensuring image clarity at high temperatures and improving the lens's image quality and heat resistance.
Smart Images
Figure CN224501033U_ABST
Abstract
Description
Technical Field ,
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[0001] The utility model relates to the technical field of projection optics, and particularly relates to a projection optical system. Background Art
[0002] With the continuous progress of projection technology and the gradual expansion of the projection market, people's requirements for projectors are also increasing. The performance of the lens plays a decisive role in the projection effect of the projector. Improving various parameters of the lens is the main development direction of major manufacturers at present. However, at present, glass aspherical surfaces are often used for projection lenses with high performance in the market, resulting in too high prices; high-brightness lenses have the phenomenon of defocusing at high and low temperatures, which causes the performance of the projector to decline after working for a period of time and the picture to become unclear; the corresponding lens parameters of low-price ones cannot meet people's needs for visual perception.
[0003] Therefore, how to achieve high brightness, high performance and ensure the clarity of the projection surface picture at high temperatures within the price range acceptable to most people is the problem we need to solve. Summary of the Utility Model
[0004] The main object of the utility model is to propose a projection optical system, aiming to improve the problem of achieving high performance, high brightness and ensuring the picture clarity at high temperatures under low-cost conditions.
[0005] To achieve the above object, the projection optical system proposed by the utility model includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens and a light-emitting chip arranged in sequence from the object side to the image side along the optical axis direction. The first lens and the second lens are set as plastic aspherical lenses, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are set as glass spherical lenses. The focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, and the focal length of the eighth lens is f8. The projection optical system satisfies the following conditions:
[0006] -40mm < f1 < -25mm; and -40mm < f2 < -25mm; and 35mm < f3 < 50mm; and 20mm < f4 < 35mm; and -20mm < f5 < -10mm; and 10mm < f6 < 20mm; and -30mm < f7 < -15mm; and 25mm < f8 < 40mm.
[0007] In an embodiment, the refractive index of the first lens is n1, 1.50 ≤ n1 ≤ 1.60;
[0008] The refractive index of the second lens is n2, where 1.50 ≤ n2 ≤ 1.60;
[0009] The refractive index of the third lens is n3, where 1.80 ≤ n3 ≤ 1.90;
[0010] The refractive index of the fourth lens is n4, where 1.55 ≤ n4 ≤ 1.65;
[0011] The refractive index of the fifth lens is n5, where 1.85 ≤ n5 ≤ 1.95;
[0012] The refractive index of the sixth lens is n6, where 1.45 ≤ n6 ≤ 1.60;
[0013] The refractive index of the seventh lens is n7, 1.85≤n5≤1.95;
[0014] The refractive index of the eighth lens is n8, where 1.85 ≤ n8 ≤ 1.95.
[0015] In one embodiment, the dispersion coefficient of the first lens is v1, where 50.0 ≤ v1 ≤ 60.0;
[0016] The dispersion coefficient of the second lens is v2, 50.0≤v2≤60.0;
[0017] The dispersion coefficient of the third lens is v3, where 30.0 ≤ v3 ≤ 40.0;
[0018] The dispersion coefficient of the fourth lens is v4, 60.0≤v4≤70.0;
[0019] The dispersion coefficient of the fifth lens is v5, 25.0≤v5≤35.0;
[0020] The dispersion coefficient of the sixth lens is v6, 75.0≤v6≤95.0;
[0021] The dispersion coefficient of the seventh lens is v7, 25.0≤v5≤35.0;
[0022] The dispersion coefficient of the eighth lens is v8, where 20.0 ≤ v8 ≤ 30.0.
[0023] In one embodiment, the first lens has a negative optical power, and the object side of the first lens is convex and the image side is concave.
[0024] The second lens has a negative optical power, and the object side and image side of the second lens are concave.
[0025] The third lens has a positive optical power, and both the object side and the image side of the third lens are convex.
[0026] The fourth lens has a positive optical power, and both the object side and the image side of the fourth lens are convex.
[0027] The fifth lens has a negative optical power, and the object side of the fifth lens is convex, while the image side is concave.
[0028] The sixth lens has a positive optical power, and both the object side and the image side of the sixth lens are convex.
[0029] The seventh lens has a negative optical power, and the object side of the seventh lens is concave while the image side is convex.
[0030] The optical power of the eighth lens is positive; the object side of the eighth lens is convex, and the image side is convex.
[0031] In one embodiment, the diameter of the first lens is D, where D ≤ 40 mm.
[0032] In one embodiment, the light-emitting chip forms a light-emitting surface on one end face facing the eighth lens, and the diameter of the light-emitting surface is IC, where IC ≤ 17.2 mm.
[0033] In one embodiment, the effective focal length of the projection optical system is EFL, the distance between the object side of the first lens and the end face of the light-emitting chip facing the eighth lens is TTL, and TTL / EFL≤9.6.
[0034] In one embodiment, both the first lens and the second lens are even-order aspherical lenses.
[0035] In one embodiment, the fifth lens, the sixth lens, and the seventh lens are connected by adhesive bonding.
[0036] In one embodiment, the projection optical system further includes an aperture stop disposed between the seventh lens and the eighth lens; and / or,
[0037] The projection optical system further includes a galvanometer and a protective glass arranged sequentially from the object side to the image side along the optical axis, with the galvanometer and the protective glass disposed between the eighth lens and the light-emitting chip.
[0038] In the technical solution of this utility model, the light emitted by the light-emitting chip sequentially enters the eighth lens, the seventh lens, the sixth lens, the fifth lens, the fourth lens, the third lens, the second lens, and the first lens, and then illuminates the projection surface to form an image. At this time, the first lens and the second lens are set as plastic aspherical lenses. Aspherical lenses have better curvature radius characteristics and have the advantages of improving distortion aberration and astigmatism. By using aspherical lenses, aberrations that occur during imaging can be eliminated as much as possible, improving edge image quality, thereby improving the image quality of the lens. Using plastic lenses can further reduce the manufacturing cost of the projection optical system. The third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are set as glass spherical lenses, so that the above lenses have good resistance to lens thermal deformation, thereby reducing the influence of temperature on the projection optical system and giving the projection optical system good thermal distortion performance. By combining materials and allocating surface shapes for multiple lenses in the projection optical system, and by rationally controlling the focal lengths of the first, second, third, fourth, fifth, sixth, seventh, and eighth lenses, the projection optical system achieves high performance, high brightness, and low cost, and maintains high clarity of the projected image during prolonged use. Attached Figure Description
[0039] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.
[0040] Figure 1 A schematic diagram of an embodiment of the projection optical system provided by this utility model;
[0041] Figure 2 for Figure 1 Schematic diagram of the optical path of a projection optical system;
[0042] Figure 3 for Figure 1 A schematic diagram of the transverse chromatic aberration curve of a central projection optical system;
[0043] Figure 4 for Figure 1 Schematic diagram of the SPOT point of the projection optical system;
[0044] Figure 5 for Figure 1 A schematic diagram of the MTF of a projection optical system.
[0045] Explanation of icon numbers:
[0046] 100. Projection optical system; 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Aperture; 10. Galvanometer; 11. Protective glass; 12. Light-emitting chip.
[0047] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0048] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0049] It should be noted that if the embodiments of this utility model involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.
[0050] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.
[0051] This invention proposes a projection optical system. It aims to address the challenge of achieving high performance, high brightness, and maintaining image clarity at high temperatures while maintaining low cost.
[0052] Please refer to Figure 1-2 , in an embodiment of the present invention, the projection optical system 100 includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, and a light-emitting chip 12 arranged in sequence from the object side to the image side along the optical axis direction. The first lens 1 and the second lens 2 are plastic aspherical lenses, and the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8 are glass spherical lenses. The focal length of the first lens 1 is f1, the focal length of the second lens 2 is f2, the focal length of the third lens 3 is f3, the focal length of the fourth lens 4 is f4, the focal length of the fifth lens 5 is f5, the focal length of the sixth lens 6 is f6, the focal length of the seventh lens 7 is f7, and the focal length of the eighth lens 8 is f8. The projection optical system 100 satisfies the following conditions: -40 mm < f1 < -25 mm; and -40 mm < f2 < -25 mm; and 35 mm < f3 < 50 mm; and 20 mm < f4 < 35 mm; and -20 mm < f5 < -10 mm; and 10 mm < f6 < 20 mm; and -30 mm < f7 < -15 mm; and 25 mm < f8 < 40 mm.
[0053] In the technical solution of this utility model, the light emitted by the light-emitting chip 12 is sequentially incident on the eighth lens 8, the seventh lens 7, the sixth lens 6, the fifth lens 5, the fourth lens 4, the third lens 3, the second lens 2, and the first lens 1, and then illuminates the projection surface for imaging. At this time, the first lens 1 and the second lens 2 are set as plastic aspherical lenses. Aspherical lenses have better curvature radius characteristics and have the advantages of improving distortion aberration and astigmatism. By using aspherical lenses, aberrations that occur during imaging can be eliminated as much as possible, improving edge image quality, thereby improving the image quality of the lens. Using plastic lenses can further reduce the manufacturing cost of the projection optical system 100. The third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8 are set as glass spherical lenses so that the above lenses have good resistance to lens thermal deformation, thereby reducing the impact of temperature on the projection optical system 100 and giving the projection optical system 100 good thermal performance. By combining materials and allocating surface shapes for the multiple lenses of the projection optical system 100, and by rationally controlling the focal lengths of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8, the projection optical system 100 achieves high performance, high brightness, and low cost, and maintains high clarity of the projected image during prolonged use.
[0054] It is understood that in this invention, the first lens 1 and the second lens 2 are made of plastic lenses. Thus, the first lens 1 and the second lens 2 are positioned away from the light-emitting chip 12. When the light-emitting chip 12 emits light, only a small amount of heat can be transferred to the first lens 1 and the second lens 2, thereby reducing the impact of temperature changes in the first lens 1 and the second lens 2 on the optical back focal length of the projection optical system 100.
[0055] Similarly, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8 are set as glass spherical lenses. This can compensate for the back focal length change caused by the temperature change of the first lens 1 and the second lens 2 during the use of the projection optical system 100, thereby ensuring clear imaging of the projection optical system 100 at high temperatures.
[0056] It should also be noted that, in a further embodiment of this utility model, both the first lens 1 and the second lens 2 are even-order aspherical lenses. This configuration allows for further correction of distortions caused by a large field of view, while also effectively correcting aberrations such as spherical aberration and chromatic aberration.
[0057] It is also understood that this utility model does not limit the specific values of the focal lengths of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8.
[0058] For example, in one embodiment of this utility model, the focal length of the first lens 1 can be set to -39mm, -37mm, -35mm, -30mm, -26mm, etc.; the focal length of the second lens 2 can be set to -39mm, -38mm, -35mm, -31mm, -25mm, etc.; the focal length of the third lens 3 can be set to 35mm, 37mm, 38mm, 40mm, 47mm, etc.; and the focal length of the fourth lens 4 can be set to 21mm, 24mm, 27mm, 31mm, etc. The focal length of the fifth lens 5 can be set to -19mm, -18mm, -15mm, -13mm, -12mm, etc.; the focal length of the sixth lens 6 can be set to 11mm, 12mm, 14mm, 15mm, 18mm, etc.; the focal length of the seventh lens 7 can be set to -28mm, -25mm, -21mm, -20mm, -17mm, etc.; the focal length of the eighth lens 8 can be set to 26mm, 28mm, 30mm, 33mm, 38mm, 19mm, etc.
[0059] In other embodiments of this utility model, the focal lengths of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8 can also be set to any value within the corresponding range. This utility model does not impose any restrictions on this, and the focal lengths can be selected according to the requirements in actual settings.
[0060] Further, in one embodiment of this utility model, the refractive index of the first lens 1 is n1, 1.50≤n1≤1.60; the refractive index of the second lens 2 is n2, 1.50≤n2≤1.60; the refractive index of the third lens 3 is n3, 1.80≤n3≤1.90; the refractive index of the fourth lens 4 is n4, 1.55≤n4≤1.65; the refractive index of the fifth lens 5 is n5, 1.85≤n5≤1.95; the refractive index of the sixth lens 6 is n6, 1.45≤n6≤1.60; the refractive index of the seventh lens 7 is n7, 1.85≤n5≤1.95; and the refractive index of the eighth lens 8 is n8, 1.85≤n8≤1.95.
[0061] Similarly, this invention does not limit the specific values of the refractive indices of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8. In one embodiment of this invention, the refractive index of the first lens 1 can be set to 1.50, 1.51, 1.52, 1.55, 1.59, etc.; the refractive index of the second lens 2 can be set to 1.50, 1.51, 1.53, 1.55, 1.58, etc.; and the refractive index of the third lens 3 can be set to 1.81, 1.83, 1.86, 1.8... The refractive index of the fourth lens 4 can be set to 1.55, 1.57, 1.58, 1.63, 1.65, etc.; the refractive index of the fifth lens 5 can be set to 1.85, 1.88, 1.89, 1.92, 1.95, etc.; the refractive index of the sixth lens 6 can be set to 1.47, 1.49, 1.50, 1.53, 1.55, 1.58, etc.; the refractive index of the seventh lens 7 can be set to 1.85, 1.86, 1.89, 1.93, 1.95, etc.; and the refractive index of the eighth lens 8 can be set to 1.87, 1.88, 1.89, 1.91, 1.94, etc.
[0062] In other embodiments of this utility model, the refractive index of the first lens 1, the refractive index of the second lens 2, the refractive index of the third lens 3, the refractive index of the fourth lens 4, the refractive index of the fifth lens 5, the refractive index of the sixth lens 6, the refractive index of the seventh lens 7, and the refractive index of the eighth lens 8 can also be set to any value within the corresponding range. This utility model does not impose any restrictions on this, and the selection can be made according to the requirements in actual settings.
[0063] Furthermore, in one embodiment of this utility model, the dispersion coefficient of the first lens 1 is v1, 50.0≤v1≤60.0; the dispersion coefficient of the second lens 2 is v2, 50.0≤v2≤60.0; the dispersion coefficient of the third lens 3 is v3, 30.0≤v3≤40.0; the dispersion coefficient of the fourth lens 4 is v4, 60.0≤v4≤70.0; the dispersion coefficient of the fifth lens 5 is v5, 25.0≤v5≤35.0; the dispersion coefficient of the sixth lens 6 is v6, 75.0≤v6≤95.0; the dispersion coefficient of the seventh lens 7 is v7, 25.0≤v5≤35.0; and the dispersion coefficient of the eighth lens 8 is v8, 20.0≤v8≤30.0.
[0064] Of course, this utility model does not limit the specific values of the dispersion coefficients of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8.
[0065] For example, in one embodiment of this utility model, the dispersion coefficient of the first lens 1 can be set to 50, 53, 55, 57, 58, etc.; the dispersion coefficient of the second lens 2 can be set to 51, 52, 55, 56, 58, 60, etc.; the dispersion coefficient of the third lens 3 can be set to 31, 33, 36, 38, 40, etc.; the dispersion coefficient of the fourth lens 4 can be set to 60, 63, 65, 66, 67, 70, etc.; the dispersion coefficient of the fifth lens 5 can be set to 26, 28, 29, 33, 34, etc.; the dispersion coefficient of the sixth lens 6 can be set to 77, 79, 80, 83, 87, 89, 90, 95, etc.; the dispersion coefficient of the seventh lens 7 can be set to 26, 29, 31, 34, 35, etc.; and the dispersion coefficient of the eighth lens 8 can be set to 20, 23, 24, 26, 29, 30, etc.
[0066] Similarly, it is understood that in other embodiments of this utility model, the dispersion coefficients of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, and the eighth lens 8 can also be set to any value within the corresponding range. This utility model does not impose any restrictions on this, and the selection can be made according to the requirements in actual settings.
[0067] In this invention, the first lens 1 has a negative optical power, its object-side surface is convex, and its image-side surface is concave; the second lens 2 has a negative optical power, its object-side surface is concave, and its image-side surface is concave; the third lens 3 has a positive optical power, its object-side surface is convex, and its image-side surface is convex; the fourth lens 4 has a positive optical power, its object-side surface is convex, and its image-side surface is convex; the fifth lens 5 has a negative optical power, its object-side surface is convex, and its image-side surface is concave; the sixth lens 6 has a positive optical power, its object-side surface is convex, and its image-side surface is convex; the seventh lens 7 has a negative optical power, its object-side surface is concave, and its image-side surface is convex; the eighth lens 8 has a positive optical power, its object-side surface is convex, and its image-side surface is convex.
[0068] In this embodiment, by setting the optical power of the first lens 1 to a negative value, it is beneficial for the projection optical system 100 to collect light, thereby effectively increasing the field of view of the projection optical system.
[0069] Meanwhile, by setting the eighth lens 8 as a lens with positive optical power, the eighth lens 8 can better correct the chromatic aberration of the projection optical system 100 and reduce the volume of the projection optical system 100.
[0070] It should also be noted that in a further embodiment of this utility model, the fifth lens 5, the sixth lens 6, and the seventh lens 7 are connected by adhesive bonding. This arrangement further reduces light energy loss, increases image clarity, and protects the scale surface, thereby optimizing the manufacturing process to meet design requirements. Furthermore, by rationally using adhesive bonding, the optical components improve the image quality of the projection optical system 100. Moreover, by bonding the three lenses, the chromatic aberration of the projection optical system 100 can be further corrected, thereby improving the color saturation of the projected image.
[0071] In another embodiment of this invention, the diameter of the first lens 1 is D, where D ≤ 40 mm. This configuration ensures the aperture of the projection optical system 100, thereby meeting the installation space requirements of the final product.
[0072] In another embodiment of this utility model, the light-emitting chip 12 forms a light-emitting surface on one end face facing the eighth lens 8, and the diameter of the light-emitting surface is IC, where IC ≤ 17.2 mm. This configuration, by limiting the maximum size of the light-emitting surface, effectively focuses light while ensuring the field of view height, thereby improving the light utilization rate of the projection optical system 100.
[0073] In another embodiment of this utility model, the effective focal length of the projection optical system 100 is EFL, and the distance between the object-side surface of the first lens 1 and the end face of the light-emitting chip 12 facing the eighth lens 8 is TTL, where TTL / EFL ≤ 9.6. This configuration further compresses the dimensions of the projection optical system 100 along the optical axis, making the structure of the projection optical system 100 compact, thereby effectively ensuring that the light emitted by the light-emitting chip 12 is focused on the projection plane, improving image clarity.
[0074] Furthermore, to enable the projection optical system 100 to adjust the light transmission amount according to actual conditions, in one embodiment of this invention, the projection optical system 100 further includes an aperture stop 9, which is disposed between the seventh lens 7 and the eighth lens 8. The aperture stop 9 can effectively control the light transmission aperture, thereby reducing stray light interference and improving image quality.
[0075] In another embodiment of this invention, the projection optical system 100 further includes a galvanometer 10 and a protective glass 11 arranged sequentially from the object side to the image side along the optical axis. The galvanometer 10 and the protective glass 11 are disposed between the eighth lens 8 and the light-emitting chip 12. With this arrangement, the light emitted by the light-emitting chip 12 can pass sequentially through the protective glass 11 and the galvanometer 10 before entering the eighth lens 8, and after passing through multiple lenses, exiting from the first lens 1, thereby realizing the projection capability of the projection optical system 100. Furthermore, the protective glass 11 provides effective protection for the light-emitting chip 12.
[0076] This utility model provides a specific embodiment of the projection optical system 100. In this embodiment, the focal length of the projection optical system 100 is f = 12.53 mm, the aperture value is F = 1.95, and the diameter of the emitting surface is IC = 17.2. In this embodiment, the basic parameters of the surface shape, radius of curvature, thickness, and material of each lens of the projection optical system 100 are shown in Table 1.
[0077] Table 1
[0078]
[0079]
[0080] Furthermore, in this embodiment, the aspherical surface shape of the aspherical lens satisfies the following condition:
[0081]
[0082] Where Z represents the distance from the vertex of the surface along the optical axis, c is the curvature of the vertex of the surface; y is the distance from the optical axis to the surface; k is the conic coefficient (when the k coefficient is less than -1, the surface curve is a hyperbola; when the k coefficient is equal to -1, it is a parabola; when the k coefficient is between -1 and 0, it is an ellipse; when the k coefficient is equal to 0, it is a circle; when the k coefficient is greater than 0, it is an oval). A, B, C, D, E, F, and G represent the fourth, sixth, eighth, tenth, twelfth, fourteenth, and sixteenth order aspherical coefficients, respectively. The shape and size of the aspherical surfaces of the object side and image side of the lens can be set by using the above parameters.
[0083] In this embodiment, the coefficients of the higher-order terms of each aspherical mirror are shown in Table 2 below:
[0084] Table 2
[0085] Face number 1 2 3 4 k -0.5095321 -0.6996908 -0.4776533 1.253431 4th order term -2.13237e-005 -1.54563e-005 0.000111651 0.000100550 6th order term -5.36478e-008 -2.69734e-007 -8.2645e-007 -4.9580e-007 8th order term 2.33283e-010 -1.09444e-009 5.24292e-009 2.91462e-009 10th-order term 8.94012e-013 1.38815e-011 -2.31620e-011 -1.14784e-011 12th order term -6.37671e-015 3.53184e-014 7.15114e-014 1.92905e-014 14th order term 1.31100e-017 -6.01240e-016 -1.9415e-016 3.55881e-018 16th order term 9.25952e-021 1.47678e-018 3.19346e-019 -2.0184e-020
[0086] It is understood that in this embodiment, surface number 1 is the object side of the first lens 1, surface number 2 is the image side of the first lens 1; surface number 3 is the object side of the second lens 2, and surface number 4 is the image side of the second lens 2.
[0087] This setup, by rationally allocating the lens power and adjusting the glass shape and material combination, effectively eliminates chromatic aberration and secondary spectrum, allowing spherical aberration, coma, astigmatism, etc. on each lens to compensate and cancel each other out, thereby achieving a clear imaging effect and realizing optimal correction of higher-order aberrations and chromatic aberration.
[0088] It should be noted that Table 2 is a design value of the aspherical coefficient of the lens in the projection optical system 100 described in this embodiment. The specific value of the aspherical coefficient design value can be adjusted according to the needs of the product, and this utility model does not limit it.
[0089] Furthermore, in this embodiment, the schematic diagram of the transverse chromatic aberration curve of the projection optical system 100 is shown below. Figure 3 As shown; a schematic diagram of the SPOT points of the projection optical system 100 is shown below. Figure 4 As shown; the MTF schematic diagram of the projection optical system 100 is shown below. Figure 5 As shown.
[0090] The above description is merely an exemplary embodiment of the present utility model and does not limit the patent scope of the present utility model. Any equivalent structural transformations made based on the technical concept of the present utility model and the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.
Claims
1. A projection optical system, characterized in that, It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a light-emitting chip that are sequentially arranged from the object side to the image side along the optical axis. The first lens and the second lens are plastic aspherical lenses. The third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are glass spherical lenses. The focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, and the focal length of the eighth lens is f8. The projection optical system satisfies the following conditions: -40 mm < f1 < -25 mm; and -40 mm < f2 < -25 mm; and 35 mm < f3 < 50 mm; and 20 mm < f4 < 35 mm; and -20 mm < f5 < -1 mm; and 10 mm < f6 < 20 mm; and -30 mm < f7 < -15 mm; and 25 mm < f8 < 40 mm.
2. The projection optical system as described in claim 1, characterized in that, The refractive index of the first lens is n1, 1.50 ≤ n1 ≤ 1.60; The refractive index of the second lens is n2, 1.50 ≤ n2 ≤ 1.60; The refractive index of the third lens is n3, 1.80 ≤ n3 ≤ 1.90; The refractive index of the fourth lens is n4, 1.55 ≤ n4 ≤ 1.65; The refractive index of the fifth lens is n5, 1.85 ≤ n5 ≤ 1.95; The refractive index of the sixth lens is n6, 1.45 ≤ n6 ≤ 1.60; The refractive index of the seventh lens is n7, 1.85 ≤ n5 ≤ 1.95; The refractive index of the eighth lens is n8, 1.85 ≤ n8 ≤ 1.
95.
3. The projection optical system as described in claim 1, characterized in that, The Abbe number of the first lens is v1, 50.0 ≤ v1 ≤ 60.0; The Abbe number of the second lens is v2, 50.0 ≤ v2 ≤ 60.0; The Abbe number of the third lens is v3, 30.0 ≤ v3 ≤ 40.0; The Abbe number of the fourth lens is v4, 60.0 ≤ v4 ≤ 70.0; The Abbe number of the fifth lens is v5, 25.0 ≤ v5 ≤ 35.0; The Abbe number of the sixth lens is v6, 75.0 ≤ v6 ≤ 95.0; The Abbe number of the seventh lens is v7, 25.0 ≤ v5 ≤ 35.0; The Abbe number of the eighth lens is v8, 20.0 ≤ v8 ≤ 30.
0.
4. The projection optical system as described in claim 1, characterized in that, The optical power of the first lens is negative. The object side surface of the first lens is convex, and the image side surface is concave; The optical power of the second lens is negative. The object side surface of the second lens is concave, and the image side surface is concave; The optical power of the third lens is positive. The object side surface of the third lens is convex, and the image side surface is convex; The optical power of the fourth lens is positive. The object side surface of the fourth lens is convex, and the image side surface is convex; The optical power of the fifth lens is negative. The object side surface of the fifth lens is convex, and the image side surface is concave; The sixth lens has a positive optical power, and both the object side and the image side of the sixth lens are convex. The seventh lens has a negative optical power, and the object side of the seventh lens is concave while the image side is convex. The optical power of the eighth lens is positive; the object side of the eighth lens is convex, and the image side is convex.
5. The projection optical system as described in claim 1, characterized in that, The diameter of the first lens is D, where D ≤ 40 mm.
6. The projection optical system as described in claim 1, characterized in that, The light-emitting chip forms a light-emitting surface on one end face facing the eighth lens, and the diameter of the light-emitting surface is IC, where IC ≤ 17.2 mm.
7. The projection optical system as claimed in claim 1, characterized in that, The effective focal length of the projection optical system is EFL, the distance between the object side of the first lens and the end face of the light-emitting chip facing the eighth lens is TTL, and TTL / EFL≤9.
6.
8. The projection optical system as described in claim 1, characterized in that, Both the first lens and the second lens are even-order aspherical lenses.
9. The projection optical system as claimed in claim 1, characterized in that, The fifth lens, the sixth lens, and the seventh lens are connected by adhesive bonding.
10. The projection optical system as claimed in claim 1, characterized in that, The projection optical system further includes an aperture stop, which is disposed between the seventh lens and the eighth lens; and / or The projection optical system further includes a galvanometer and a protective glass arranged sequentially from the object side to the image side along the optical axis, with the galvanometer and the protective glass disposed between the eighth lens and the light-emitting chip.