Projection optical system

Abstract

The invention discloses a projection optical system, and relates to the technical field of projection optics, and the projection optical system comprises 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 which are sequentially arranged from the object side to the image side in the optical axis direction. The first lens and the second lens are plastic aspheric lenses, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are glass spherical lenses, and the projection optical system meets the following conditions:-40mmlt; f1lt; 25 mm; the thickness is-40 mmlt; f2lt; f2lt; 25 mm; the thickness is 35 mmlt; f3lt; f3t; the thickness is 50 mm; the thickness is 20 mmlt; f4lt; f4t; 35 mm; the thickness is-20 mmlt; f5lt; f5t; 10 mm; the thickness is 10 mmlt; f61t; f61t; 20 mm; the thickness is-30 mmlt; f7lt; f7lt; 15 mm; the thickness is 25 mmlt; f81t; f81t; the thickness is 40mm. According to the arrangement, through material combination and surface type distribution of the plurality of lenses of the projection optical system and reasonable control of the focal length of the plurality of lenses, the projection optical system has the effects of high performance, high brightness and low cost, and the projection optical system can keep high definition of a projection picture in a long-time use process.

Description

Technical Field

[0001] The present invention 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 have also increased. 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 lenses are often used for projection lenses with high performance in the market, resulting in too high prices; high-brightness lenses have defocus phenomena at high and low temperatures, causing 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 lenses 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 a problem that needs to be solved by us. Summary of the Invention

[0004] The main object of the present invention 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 present invention 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 sequentially arranged 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, and 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, 1.50≤n2≤1.60;

[0009] The refractive index of the third lens is n3, 1.80≤n3≤1.90;

[0010] The refractive index of the fourth lens is n4, 1.55≤n4≤1.65;

[0011] The refractive index of the fifth lens is n5, 1.85≤n5≤1.95;

[0012] The refractive index of the sixth lens is n6, 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, 1.85≤n8≤1.95.

[0015] In one embodiment, the Abbe coefficient of the first lens is v1, 50.0≤v1≤60.0;

[0016] The dispersion coefficient of the second lens is v2, 50.0≤v2≤60.0;

[0017] The Abbe coefficient of the third lens is v3, 30.0≤v3≤40.0;

[0018] The Abbe coefficient of the fourth lens is v4, 60.0≤v4≤70.0;

[0019] The Abbe number of the fifth lens is v5, 25.0≤v5≤35.0;

[0020] The sixth lens has an Abbe number of v6, 75.0≤v6≤95.0;

[0021] The Abbe number of the seventh lens is v7, 25.0≤v5≤35.0;

[0022] The Abbe coefficient of the eighth lens is v8, 20.0≤v8≤30.0.

[0023] In one embodiment, 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;

[0024] The optical power of the second lens is negative, and the object-side surface and image-side surface of the second lens are concave;

[0025] The third lens has a positive optical power, and its object-side surface and image-side surface are convex.

[0026] The fourth lens has a positive optical power, and its object-side surface and image-side surface are convex.

[0027] 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;

[0028] The sixth lens has a positive optical power, and its object-side surface and image-side surface are convex.

[0029] The seventh lens has a negative optical power, and its object-side surface is concave and its image-side surface is convex.

[0030] The optical power of the eighth lens is positive; the object-side surface and the image-side surface of the eighth lens are convex.

[0031] In one embodiment, the diameter of the first lens is D, where D≤40 mm.

[0032] In one embodiment, an end surface of the light-emitting chip facing the eighth lens forms a light-emitting surface, and a 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 surface of the first lens and an end surface 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 aspheric lenses.

[0035] In one embodiment, the fifth lens, the sixth lens, and the seventh lens are connected by cementation.

[0036] In one embodiment, the projection optical system further includes an aperture, and the aperture is provided between the seventh lens and the eighth lens; and / or,

[0037] The projection optical system further includes a galvanometer mirror and a protective glass sequentially arranged from the object side to the image side along the optical axis, wherein the galvanometer mirror and the protective glass are arranged between the eighth lens and the light-emitting chip.

[0038] In the technical solution of the present invention, the light emitted by the light-emitting chip is sequentially incident on 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 irradiated onto the projection surface for imaging. At this time, the first lens and the second lens are set as plastic aspheric lenses. Aspheric lenses have better curvature radius characteristics and have the advantages of improving distortion aberration, astigmatism, and aberration. After using aspheric lenses, aberrations occurring during imaging can be eliminated as much as possible, and edge image quality can be improved, thereby improving the imaging quality of the lens. The use of plastic lenses can further reduce the manufacturing cost of the projection optical system; and 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 thermal deformation of the lenses, thereby reducing the influence of temperature on the projection optical system, and the projection optical system has good athermal performance. In this way, by combining the materials and distributing the surface shapes of the multiple lenses of the projection optical system, and reasonably controlling the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens, the projection optical system has high performance, high brightness, and low cost, and can maintain high definition of the projection image during long-term use. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0040] Figure 1 A schematic structural diagram of an embodiment of a projection optical system provided by the present invention;

[0041] Figure 2 for Figure 1 Schematic diagram of the optical path of the projection optical system;

[0042] Figure 3 for Figure 1 Schematic diagram of vertical axis chromatic aberration curve of the 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 MTF diagram of the projection optical system.

[0045] Description of Figure 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 purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0050] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] The present invention proposes a projection optical system, which aims to improve the problem of how to achieve high performance and high brightness at low cost while ensuring image clarity at high temperatures.

[0052] See also 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 that are sequentially arranged from the object side to the image side along the optical axis direction. The first lens 1 and the second lens 2 are configured as 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 configured as glass spherical lenses. The focal length of the first lens 1 is f1, the focal length of the second lens 2 is f , 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 the present invention, 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 irradiated onto the projection surface for imaging. At this time, the first lens 1 and the second lens 2 are configured as plastic aspheric lenses. Aspheric lenses have better curvature radius characteristics and have the advantages of improving distortion aberration, astigmatism, and aberration. After using aspheric lenses, aberrations occurring during imaging can be eliminated as much as possible, improving edge image quality, thereby improving the imaging 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 configured as glass spherical lenses. This allows the above lenses to have good resistance to thermal deformation, thereby reducing the impact of temperature on the projection optical system 100, and providing the projection optical system 100 with good athermal performance. In this way, by combining the materials and distributing the surface shapes of the multiple lenses of the projection optical system 100, and reasonably 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 has high performance, high brightness and low cost, and can maintain high definition of the projection image during long-term use.

[0054] It can be understood that in the present invention, the first lens 1 and the second lens 2 are set as plastic lenses. In this way, the first lens 1 and the second lens 2 are set 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, so as to reduce the influence of the temperature change of the first lens 1 and the second lens 2 on the optical back focus of the projection optical system 100.

[0055] Similarly, 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 are set as glass spherical lenses. In this way, the back focus 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 can be compensated, 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 the present invention, both the first lens 1 and the second lens 2 are even-order aspheric lenses. This arrangement further corrects distortion caused by a large field of view, while effectively correcting aberrations such as spherical aberration and chromatic aberration.

[0057] It can also be understood that the present invention 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 the present invention, 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.; the focal length of the fourth lens 4 can be set to 21mm, 24mm, 27mm, 31mm, 3 4mm, 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 the present invention, the focal length of the first lens 1, the focal length of the second lens 2, the focal length of the third lens 3, the focal length of the fourth lens 4, the focal length of the fifth lens 5, the focal length of the sixth lens 6, the focal length of the seventh lens 7, and the focal length of the eighth lens 8 can also be set to any value within the corresponding range. The present invention does not impose any limitation on this. In actual setting, it can be selected according to needs.

[0060] Furthermore, in one embodiment of the present invention, 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, the present 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 the present 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.; the refractive index of the third lens 3 can be set to 1.81, 1.83, 1.86, 1.88, etc. 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.; 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 the present invention, 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 may also be set to any value within the corresponding range. The present invention does not impose any limitation on this, and in actual setting, it can be selected according to needs.

[0063] Furthermore, in one embodiment of the present invention, 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, the present invention does not limit the specific values ​​of the chromatic aberration 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 the present invention, 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] It is also understandable that, in other embodiments of the present invention, the dispersion coefficient of the first lens 1, the dispersion coefficient of the second lens 2, the dispersion coefficient of the third lens 3, the dispersion coefficient of the fourth lens 4, the dispersion coefficient of the fifth lens 5, the dispersion coefficient of the sixth lens 6, the dispersion coefficient of the seventh lens 7, and the dispersion coefficient of the eighth lens 8 can also be set to any value within the corresponding range. The present invention does not impose any limitation on this. In actual setting, it can be selected according to needs.

[0067] In the present invention, the optical power of the first lens 1 is negative, the object side surface of the first lens 1 is convex, and the image side surface is concave; the optical power of the second lens 2 is negative, the object side surface of the second lens 2 is concave, and the image side surface is concave; the optical power of the third lens 3 is positive, the object side surface of the third lens 3 is convex, and the image side surface is convex; the optical power of the fourth lens 4 is positive, the object side surface of the fourth lens 4 is convex, and the image side surface is convex; the optical power of the fifth lens 5 is negative, the object side surface of the fifth lens 5 is convex, and the image side surface is concave; the optical power of the sixth lens 6 is positive, the object side surface of the sixth lens 6 is convex, and the image side surface is convex; the optical power of the seventh lens 7 is negative, the object side surface of the seventh lens 7 is concave, and the image side surface is convex; the optical power of the eighth lens 8 is positive, and the object side surface of the eighth lens 8 is convex, and the 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 possible to facilitate the collection of light by the projection optical system 100, thereby effectively increasing the field of view of the projection optical system.

[0069] At the same time, by setting the eighth lens 8 as a lens with positive refractive power, the eighth lens 8 can better correct the chromatic aberration of the projection optical system 100 and compress the volume of the projection optical system 100.

[0070] It should also be noted that, in a further embodiment of the present invention, the fifth lens 5, the sixth lens 6, and the seventh lens 7 are connected by gluing. This arrangement can further reduce light energy loss, increase imaging clarity, and protect the scale surface, thereby optimizing the processing flow to meet design requirements. By rationally using glued parts, the optical components can improve the image quality of the projection optical system 100. Furthermore, by arranging the three lenses for gluing, chromatic aberration of the projection optical system 100 can be further corrected, thereby improving the color saturation of the projection image of the projection optical system 100.

[0071] In another embodiment of the present invention, the diameter of the first lens 1 is D, D≤40 mm. This configuration can ensure the aperture of the projection optical system 100 and thus meet the installation space requirements of the final product.

[0072] In another embodiment of the present invention, the light-emitting chip 12 forms a light-emitting surface on one end surface facing the eighth lens 8. The diameter of the light-emitting surface is IC, where IC is ≤ 17.2 mm. This configuration effectively focuses light while ensuring a high field of view, thereby improving the light utilization efficiency of the projection optical system 100.

[0073] In yet another embodiment of the present invention, the effective focal length of the projection optical system 100 is EFL, the distance between the object-side surface of the first lens 1 and the end surface of the light-emitting chip 12 facing the eighth lens 8 is TTL, and TTL / EFL ≤ 9.6. This configuration further reduces the size of the projection optical system 100 along the optical axis, making the projection optical system 100 compact, thereby effectively ensuring that light emitted by the light-emitting chip 12 is focused on the projection plane, and improving imaging clarity.

[0074] Furthermore, to enable the projection optical system 100 to adjust the amount of light passing through according to actual conditions, in one embodiment of the present invention, the projection optical system 100 further includes an aperture 9, which is disposed between the seventh lens 7 and the eighth lens 8. The provision of the aperture 9 can effectively control the light passing aperture, thereby reducing the interference of stray light and improving imaging quality.

[0075] In another embodiment of the present invention, the projection optical system 100 further includes a galvanometer mirror 10 and a protective glass 11, which are sequentially arranged along the optical axis from the object side to the image side. The galvanometer mirror 10 and the protective glass 11 are disposed between the eighth lens 8 and the light-emitting chip 12. With this arrangement, light emitted by the light-emitting chip 12 can sequentially pass through the protective glass 11 and the galvanometer mirror 10 before entering the eighth lens 8 and, after passing through multiple lenses, exiting from the first lens 1, thereby achieving the projection capability of the projection optical system 100. Furthermore, the provision of the protective glass 11 can provide effective protection for the light-emitting chip 12.

[0076] The present invention provides a specific embodiment of the projection optical system 100. In this embodiment, the focal length f of the projection optical system 100 is 12.53 mm, the aperture value F is 1.95, and the light-emitting surface diameter IC is 17.2. In this embodiment, the basic parameters of the surface shape, curvature radius, 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 aspheric surface shape of the aspheric lens satisfies the following conditions:

[0081]

[0082] Among them, Z represents the distance of the surface from the vertex of the surface in the direction of 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 cone 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, and when the k coefficient is greater than 0, it is an oblate) A, B, C, D, E, F, and G represent the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, and sixteenth-order aspheric coefficients respectively. The above parameters can be used to set the shape and size of the aspheric surfaces of the object side and image side of the lens.

[0083] In this embodiment, the high-order coefficients of each aspherical mirror surface can be seen from the following Table 2:

[0084] Table 2

[0085] Surface 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 can be understood that, in this embodiment, surface number 1 is the object-side surface of the first lens 1, and surface number 2 is the image-side surface of the first lens 1; surface number 3 is the object-side surface of the second lens 2, and surface number 4 is the image-side surface of the second lens 2.

[0087] This setting, through the reasonable distribution of lens optical power, adjustment of glass shape and material matching, effectively eliminates chromatic aberration and secondary spectrum, so that the spherical aberration, coma, astigmatism, etc. on each lens compensate and offset each other to achieve a clear imaging effect, and realize the optimal correction of high-order aberrations and chromatic aberrations.

[0088] It should be noted that Table 2 is a design value of the aspheric coefficient of the lens in the projection optical system 100 described in this embodiment. The specific numerical value of the aspheric coefficient design value can be adjusted according to product requirements, and the present invention does not impose any limitation on this.

[0089] In addition, in this embodiment, the vertical axis chromatic aberration curve of the projection optical system 100 is shown as follows: Figure 3 The SPOT point diagram of the projection optical system 100 is shown as follows: Figure 4 The MTF diagram of the projection optical system 100 is shown as follows: Figure 5 shown.

[0090] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

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 arranged in sequence 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: -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.

2. The projection optical system according to claim 1, wherein: 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 according to claim 1, wherein: 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 according to claim 1, wherein: 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 its object-side surface and image-side surface are convex. The seventh lens has a negative optical power, and its object-side surface is concave and its image-side surface is convex. The optical power of the eighth lens is positive; the object-side surface and the image-side surface of the eighth lens are convex.

5. The projection optical system according to claim 1, wherein: The diameter of the first lens is D, and D≤40 mm.

6. The projection optical system according to claim 1, wherein: An end surface of the light-emitting chip facing the eighth lens forms a light-emitting surface, and a diameter of the light-emitting surface is IC, where IC is less than or equal to 17.2 mm.

7. The projection optical system according to claim 1, wherein: The effective focal length of the projection optical system is EFL, the distance between the object side surface of the first lens and an end surface of the light-emitting chip facing the eighth lens is TTL, and TTL / EFL≤9.

6.

8. The projection optical system according to claim 1, wherein: Both the first lens and the second lens are even-order aspheric lenses.

9. The projection optical system according to claim 1, wherein: The fifth lens, the sixth lens, and the seventh lens are connected by gluing.

10. The projection optical system according to claim 1, wherein: The projection optical system further includes an aperture, and the aperture is provided between the seventh lens and the eighth lens; and / or, The projection optical system further includes a galvanometer mirror and a protective glass sequentially arranged from the object side to the image side along the optical axis, wherein the galvanometer mirror and the protective glass are arranged between the eighth lens and the light-emitting chip.

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