Long-focus projection optical system and projection equipment

Abstract

The utility model provides a long-focus projection optical system and projection equipment, and belongs to the technical field of optical imaging. The long-focus projection optical system comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with positive focal power, a seventh lens with negative focal power and an eighth lens with positive focal power. The long-focus projection optical system comprises a first lens with a positive focal power, a second lens with a positive focal power, a third lens with a positive focal power, a ninth lens with a positive focal power, a tenth lens with a positive focal power and a light valve, so that the total optical length of the long-focus projection optical system is controlled within 76.85 mm, the definition reaches more than 1080P, and the aperture value is 2.0-2.6; wherein the first lens is a plastic aspheric lens, and the other lenses are spherical lenses. According to the scheme, the ten lenses are adopted, and the focal power and the shape matching relation of the lenses are reasonably set, so that the long-focus projection optical system which is small in size, high in resolution, low in cost, small in projection ratio and free of virtual focus at high temperature is realized.

Description

Technical Field

[0001] The utility model relates to the technical field of optical imaging, in particular to a long-focus projection optical system and projection equipment. Background Art

[0002] With the development of projection technology in recent years, projectors have been widely used in home, education, office and other fields. Common projection equipment on the market is realized by direct projection. At present, there is a common problem that it cannot take into account small size, low cost, high resolution, and no defocus at high temperature. For example, some lenses sacrifice part of the resolution or use plastic aspherical surfaces to reduce costs. However, due to the high heat generated by the projector, such lenses are often prone to defocus due to high temperature, affecting the use effect; while some lenses have high imaging quality, but are expensive and are not recognized by the consumer market. Utility Model Content

[0003] The main purpose of the utility model is to provide a long-focus projection optical system and projection equipment, aiming to provide a small-volume, high-resolution, low-cost, high-temperature and non-false-focus long-focus projection optical system.

[0004] To achieve the above-mentioned purpose, the utility model proposes a telephoto projection optical system, which has an object side and an image side that are arranged opposite to each other along the optical axis direction, and the telephoto projection optical system includes a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, a ninth lens with positive optical power, a tenth lens with positive optical power and a light valve, which are arranged in sequence from the object side to the image side, so that the total optical length of the telephoto projection optical system is controlled within 76.85 mm, the definition reaches above 1080P, and the aperture value is between 2.0 and 2.6;

[0005] Among them, the first lens is a plastic aspherical lens, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are spherical lenses.

[0006] In one embodiment, the telephoto projection optical system further includes an aperture stop, and the aperture stop is disposed between the fourth lens and the fifth lens.

[0007] In one embodiment, the telephoto projection optical system further includes an image biasing mirror and an illumination prism which are sequentially arranged between the tenth lens and the light valve from the object side to the image side.

[0008] In one implementation, the second lens is cemented to the third lens, and the fifth lens, the sixth lens and the seventh lens are cemented to each other.

[0009] In one embodiment, the first lens is a meniscus lens, and its object-side surface is a convex surface;

[0010] The second lens is a biconcave lens;

[0011] The third lens is a biconvex lens;

[0012] The fourth lens is a meniscus lens, and its object side surface is a convex surface;

[0013] The fifth lens is a biconcave lens;

[0014] The sixth lens is a biconvex lens;

[0015] The seventh lens is a meniscus lens, and its object side surface is concave;

[0016] The eighth lens is a meniscus lens, and its object side surface is concave;

[0017] The ninth lens is a biconvex lens;

[0018] The tenth lens is a biconvex lens.

[0019] In one embodiment, 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, the focal length of the eighth lens is f8, the focal length of the ninth lens is f9, and the focal length of the tenth lens is f10, wherein:

[0020] -60<f1<-10, -60<f2<-10, 10<f3<60, 10<f4<60, -60<f5<-1 0, 10<f6<60, -60<f7<-10, 10<f8<60, 10<f9<70, 10<f10<60.

[0021] In one embodiment, the refractive index of the first lens is n1, and the dispersion coefficient is v1; the refractive index of the second lens is n2, and the dispersion coefficient is v2; the refractive index of the third lens is n3, and the dispersion coefficient is v3; the focal refractive index of the fourth lens is n4, and the dispersion coefficient is v4; the refractive index of the fifth lens is n5, and the dispersion coefficient is v5; the refractive index of the sixth lens is n6, and the dispersion coefficient is v6; the refractive index of the seventh lens is n7, and the dispersion coefficient is v7; the refractive index of the eighth lens is n8, and the dispersion coefficient is v8; the refractive index of the ninth lens is n9, and the dispersion coefficient is v9; the refractive index of the tenth lens is n10, and the dispersion coefficient is v10, wherein:

[0022] 1.40≤n1≤1.60, 1.60≤n2≤1.80, 1.70≤n3≤1.90, 1.80≤n4≤2.00, 1.50≤n5≤1.70, 1.50≤n6≤1.70, 1.70≤n7≤1.90, 1.50≤n8≤1.70, 1.70≤n9≤1.90, 1.70≤n10≤1.90, 50.0≤v1≤70.0, 20.0≤v2≤40.0, 30.0≤v3≤50.0, 20.0≤v4≤40.0, 20.0≤v5≤40.0, 40.0≤v6≤90.0, 20.0≤v7≤40.0, 40.0≤v8≤90.0, 40.0≤v9≤60.0, 40.0≤v10≤60.0.

[0023] In one embodiment, the distance from the tenth lens to the light valve is BFL, and the total optical length of the telephoto projection optical system is TTL, wherein:

[0024] 0.05<BFL / TTL<1.

[0025] In one embodiment, the total optical length of the telephoto projection optical system is TTL, the diameter of the first lens is D1, and the image plane diameter of the telephoto projection optical system is IC, wherein:

[0026] 50mm<TTL<60mm, D1<27mm, IC≤15.8mm.

[0027] The utility model also proposes a projection device, the projection device comprising the above-mentioned telephoto projection optical system, the telephoto projection optical system having an object side and an image side arranged opposite to each other along the optical axis direction, the telephoto projection optical system comprising a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with positive focal power, a seventh lens with negative focal power, an eighth lens with positive focal power, a ninth lens with positive focal power, a tenth lens with positive focal power and a light valve, which are arranged in sequence from the object side to the image side, so that the total optical length of the telephoto projection optical system is controlled within 76.85 mm, the definition reaches above 1080P, and the aperture value is between 2.0 and 2.6;

[0028] Among them, the first lens is a plastic aspherical lens, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are spherical lenses.

[0029] The technical solution provided by the utility model is that by setting the first lens with negative focal power, it is beneficial to the collection of light in the optical system, which can effectively shorten the projection distance and reduce the projection ratio; by setting the tenth lens with positive focal power, it bears the larger focal power of the system, changes the propagation direction of the light beam, corrects the aberration of the off-axis field of view, and is more conducive to the imaging of the light beam on the image plane; by setting the first lens as a plastic aspheric lens, the proportion of glass lenses used is reduced, the cost is reduced, and various aberrations are corrected, the edge image quality is improved, the imaging quality is high, and the clarity can reach above 1080P; by setting other lenses as spherical lenses, the aberration is effectively improved, and it is ensured that it does not defocus under high temperature conditions; the light trend of the optical system is smooth, and the structure is more compact while introducing more light, and the total optical length is controlled within 76.85mm. In terms of aperture, the aperture value F satisfies 2.0≤F≤2.6, and the optical system can also clearly image in weak light, and by reasonably setting the focal length ratio, the optical system has good heat elimination and more stable working performance. By using ten lenses and reasonably setting the optical focal length and shape matching relationship of each lens, a long-focus projection optical system with small volume, small projection ratio, low cost, high resolution and good heat elimination is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0031] Figure 1 A schematic structural diagram of an embodiment of a long-focus projection optical system provided by the utility model;

[0032] Figure 2 for Figure 1 MTF diagram of medium and long focal length projection optical system;

[0033] Figure 3 for Figure 1 Schematic diagram of the SPOT point of the medium and long focal length projection optical system.

[0034] Description of Figure Numbers:

[0035] 1000. Telephoto 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. ninth lens; 10. tenth lens; a. aperture stop; b. image biasing mirror; c. illumination prism; d. light valve.

[0036] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0038] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0039] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the 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 contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0040] With the development of projection technology in recent years, projectors have been widely used in home, education, office and other fields. Common projection equipment on the market is realized by direct projection. At present, there is a common problem that it cannot take into account small size, low cost, high resolution, and no defocus at high temperature. For example, some lenses sacrifice part of the resolution or use plastic aspherical surfaces to reduce costs. However, due to the high heat generated by the projector, such lenses are often prone to defocus due to high temperature, affecting the use effect; while some lenses have high imaging quality, but are expensive and are not recognized by the consumer market.

[0041] The main purpose of the utility model is to propose a telephoto projection optical system and projection equipment, aiming to provide a telephoto projection optical system with small volume, high resolution, low cost, small projection ratio and no false focus at high temperature.

[0042] See also Figure 1 The utility model provides a telephoto projection optical system 1000, which has an object side and an image side arranged opposite to each other along the optical axis direction. The telephoto projection optical system 1000 includes a first lens 1 with negative optical power, a second lens 2 with negative optical power, a third lens 3 with positive optical power, a fourth lens 4 with positive optical power, a fifth lens 5 with negative optical power, a sixth lens 6 with positive optical power, a seventh lens 7 with negative optical power, an eighth lens 8 with positive optical power, and a fifth lens 9 with positive optical power. A ninth lens 9 with a positive optical power, a tenth lens 10 with a positive optical focal power and a light valve d are provided, so that the total optical length of the telephoto projection optical system 1000 is controlled within 76.85 mm, the definition reaches above 1080P, and the aperture value is between 2.0 and 2.6; wherein the first lens 1 is a plastic aspherical lens, and the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7, the eighth lens 8, the ninth lens 9 and the tenth lens 10 are spherical lenses.

[0043] The technical solution provided by the utility model is that by setting the first lens 1 with negative focal power, it is beneficial to the collection of light in the optical system, which can effectively shorten the projection distance and reduce the projection ratio; by setting the tenth lens 10 with positive focal power, it bears the larger focal power of the system, changes the propagation direction of the light beam, corrects the aberration of the off-axis field of view, and is more conducive to the imaging of the light beam on the image plane; by setting the first lens 1 as a plastic aspheric lens, the proportion of glass lenses used is reduced, the cost is reduced, and various aberrations are corrected, the edge image quality is improved, the imaging quality is high, and the clarity can reach above 1080P; by setting other lenses as spherical lenses, the aberration is effectively improved, and it is ensured that it does not defocus under high temperature conditions; the light trend of the optical system is smooth, and the structure is more compact while introducing more light, and the total optical length is controlled within 76.85mm. In terms of aperture, the aperture value F satisfies 2.0≤F≤2.6, and the optical system can also clearly image in weak light, and by reasonably setting the focal length ratio, the optical system has good heat elimination and more stable working performance. By using ten lenses and reasonably setting the optical focal length and shape matching relationship of each lens, a long-focus projection optical system 1000 with small volume, small projection ratio, low cost, high resolution and good heat elimination is achieved.

[0044] It should be noted that the characteristic of an aspherical lens is that the curvature changes continuously from the center of the lens to the periphery of the lens, which is different from a spherical lens that has a constant curvature from the center of the lens to the periphery of the lens.

[0045] Furthermore, the telephoto projection optical system 1000 further includes an aperture stop, which is disposed between the fourth lens 4 and the fifth lens 5. The aperture stop a limits the aperture of the light beam on the optical axis, intercepts part of the light, thereby reducing the light spot, improving the image contrast, and also expanding the target surface and improving the image quality. According to actual conditions, adjusting the light flux of the aperture stop a helps to further improve the imaging quality.

[0046] Furthermore, the telephoto projection optical system 1000 further includes an image biasing mirror b and an illumination prism c which are sequentially arranged between the tenth lens 10 and the light valve d from the object side to the image side. By arranging the illumination prism c, the light can be effectively controlled and directed to ensure that the illuminated object or area can be properly illuminated; by arranging the image biasing mirror b, aberrations, distortions and other optical problems in the optical system can be adjusted or corrected to obtain a clear and accurate image.

[0047] Furthermore, in order to improve the image quality of the optical system, reduce the loss of light energy, increase the image clarity, protect the scale surface, and further optimize the processing flow to meet the design requirements, the second lens 2 is glued to the third lens 3, and the fifth lens 5, the sixth lens 6 and the seventh lens 7 are glued to each other. In this way, the glued parts are used reasonably and the optical power is reasonably distributed, which can well correct the aberration and achieve the effect of high temperature athermalization. It also effectively reduces chromatic aberration and improves the clarity of imaging.

[0048] Specifically, in a preferred embodiment, please refer to Figure 1 , the first lens 1 is a concave-convex lens, and its object-side surface is convex; the second lens 2 is a biconcave lens; the third lens 3 is a biconvex lens; the fourth lens 4 is a concave-convex lens, and its object-side surface is convex; the fifth lens 5 is a biconcave lens; the sixth lens 6 is a biconvex lens; the seventh lens 7 is a concave-convex lens, and its object-side surface is concave; the eighth lens 8 is a concave-convex lens, and its object-side surface is concave; the ninth lens 9 is a biconvex lens; and the tenth lens 10 is a biconvex lens.

[0049] Further, 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 7, the focal length of the eighth lens 8 is f8, the focal length of the ninth lens 9 is f9, and the focal length of the tenth lens 10 is f10, wherein: -60<f1<-10, -60<f2<-10, 10<f3<60, 10<f4<60, -60<f5<-10, 10<f6<60, -60<f7<-10, 10<f8<60, 10<f9<70, 10<f10<60. This embodiment is a preferred embodiment. By combining different lenses and reasonably allocating their optical powers, the entire optical system has good performance such as low cost and high pixel.

[0050] Further, the refractive index of the first lens 1 is n1, and the dispersion coefficient is v1; the refractive index of the second lens 2 is n2, and the dispersion coefficient is v2; the refractive index of the third lens 3 is n3, and the dispersion coefficient is v3; the focal refractive index of the fourth lens 4 is n4, and the dispersion coefficient is v4; the refractive index of the fifth lens 5 is n5, and the dispersion coefficient is v5; the refractive index of the sixth lens 6 is n6, and the dispersion coefficient is v6; the refractive index of the seventh lens 7 is n7, and the dispersion coefficient is v7; the refractive index of the eighth lens 8 is n8, and the dispersion coefficient is v8; the refractive index of the ninth lens 9 is n9, and the dispersion coefficient is v9; the refractive index of the tenth lens 10 is n10, and the dispersion coefficient is v10, wherein: 1.40≤n1≤1. 60, 1.60≤n2≤1.80, 1.70≤n3≤1.90, 1.80≤n4≤2.00, 1.50≤n5≤1.70, 1.50≤n6≤1.70, 1.70≤n7≤1.90, 1.50≤n8≤1.70, 1.70≤n9≤1.90, 1.70≤n10≤1.90, 50.0≤ v1≤70.0, 20.0≤v2≤40.0, 30.0≤v3≤50.0, 20.0≤v4≤40.0, 20.0≤v5≤40.0, 40.0≤v6≤90.0, 20.0≤v7≤40.0, 40.0≤v8≤90.0, 40.0≤v9≤60.0, 40.0≤v10≤60.0. This embodiment is a preferred embodiment, through the mutual combination of different lenses and the reasonable allocation of their refractive index and dispersion coefficient, the telephoto projection optical system 1000 has the performances of low cost, high pixel and good athermal difference.

[0051] In an embodiment provided by the present invention, the distance from the tenth lens 10 to the light valve d is BFL, and the total optical length of the telephoto projection optical system 1000 is TTL, wherein: 0.05<BFL / TTL<1. By reasonably limiting the size of BFL, the size of the total optical length can be further limited, making the entire optical system more compact, which helps to control the focal length of the telephoto projection optical system 1000.

[0052] In an embodiment provided by the present utility model, the total optical length of the telephoto projection optical system 1000 is TTL, the diameter of the first lens 1 is D1, and the image plane diameter of the telephoto projection optical system 1000 is IC, wherein: 50mm<TTL<60mm, D1<27mm, IC≤15.8mm. In this design, by limiting the numerical relationship of the above optical system characteristics, it is possible to avoid the aperture of the telephoto projection optical system 1000 being too large to meet the installation space requirements of the final product, and by limiting the specific values ​​of the total optical length and the diameter of the first lens 1, the lens size can be appropriately limited, which is conducive to miniaturization of the lens.

[0053] It is worth mentioning that the surface shape of the aspheric lens in the telephoto projection optical system 1000 described in this embodiment should satisfy the following equation:

[0054]

[0055] Among them, c is the curvature corresponding to the radius; y is the radial coordinate (its unit is the same as the lens length unit); k is the conic coefficient, and A, B, C, D, E, F, G... respectively represent the fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, fourteenth-order, sixteenth-order... aspheric coefficients. The above parameters can be used to set the shape and size of the aspheric surface of the lens facing the object side and the image side.

[0056] Among them, when k<-1, the corresponding surface curve of the lens is a hyperbola; when k=-1, the corresponding surface curve of the lens is a parabola; when -1<k<0, the corresponding surface curve of the lens is an ellipse; when k=0, the corresponding surface curve of the lens is a circle; when k>0, the corresponding surface curve of the lens is an oblate circle.

[0057] It should be noted that the basic parameter table of the telephoto projection optical system 1000 in an embodiment provided by the present invention is shown in Table 1, wherein the units of the curvature radius and thickness are both millimeters (mm).

[0058] Table 1

[0059]

[0060]

[0061] In this embodiment, the aspheric coefficients of the aspheric lens in the telephoto projection optical system 1000 include: the quadratic surface coefficient k, the fourth-order aspheric coefficient A, the sixth-order aspheric coefficient B, the eighth-order aspheric coefficient C, the tenth-order aspheric coefficient D, the twelfth-order aspheric coefficient E, the fourteenth-order aspheric coefficient F, and the sixteenth-order aspheric coefficient G of the surface, as shown in Table 2 below.

[0062] Table 2

[0063] Face number k A B C D E F G 1 -3.76 -5.0E-05 -9.3E-07 2.8E-08 -3.1E-10 1.8E-12 -5.9E-15 7.8E-18 2 -0.73 -5.0E-04 1.4E-06 -2.0E-08 9.4E-10 -2.3E-11 2.3E-13 -9.1E-16

[0064] Please refer to Figure 2 , is a schematic diagram of the MTF of the telephoto projection optical system 1000 in this embodiment, which shows the imaging quality of three wavelengths of light, wherein the horizontal axis represents the number of line pairs, and the vertical axis represents the resolution capability, wherein the higher the value of the vertical axis, the stronger the resolution capability and the higher the image quality restoration degree, wherein the MTF values ​​are all greater than 0.6, indicating that the imaging quality is very clear.

[0065] Please refer to Figure 3 , is a schematic diagram of the spot SPOT of the telephoto projection optical system 1000 in this embodiment, which shows a schematic diagram of the imaging of the spot of three different wavelengths of light on the screen under a certain field of view under normalized different field of view conditions. Figure 3 It can be seen that the image points of this optical system at different field positions are smaller and the colors are more concentrated, indicating that the imaging quality is better.

[0066] In this embodiment, the focal length of the telephoto projection optical system 1000 is 12.46 mm, the aperture value is 2.4, the image plane diameter is 15.8 mm, the total optical length is only 59.5 mm, the maximum aperture of the lens is 27 mm, and the projection ratio is 1.2, which ensures that various aberrations of the lens are corrected, improves edge image quality, has high imaging quality, and can produce clear images even in low light. The lens size is small, the projection ratio is small, and the thermal stability is excellent. The optical system does not have obvious thermal defocusing phenomenon at higher temperatures, especially when the temperature deviation of the entire group is no more than 20°C, it still maintains good performance and more stable working performance.

[0067] The utility model further proposes a projection device, which includes the above-mentioned telephoto projection optical system 1000. Since the projection device includes the telephoto projection optical system 1000, the specific structure of the telephoto projection optical system 1000 refers to the above-mentioned embodiment. Since the telephoto projection optical system 1000 of the projection device adopts all the technical solutions of all the above-mentioned embodiments, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be described one by one here.

[0068] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A telephoto projection optical system, characterized in that: The telephoto projection optical system has an object side and an image side which are arranged opposite to each other along the optical axis direction, and comprises a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, an eighth lens with positive optical power, a ninth lens with positive optical power, a tenth lens with positive optical power and a light valve, which are arranged in sequence from the object side to the image side, so that the total optical length of the telephoto projection optical system is controlled within 76.85 mm, the definition reaches above 1080P, and the aperture value is between 2.0 and 2.6; Among them, the first lens is a plastic aspherical lens, and the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are spherical lenses.

2. The telephoto projection optical system according to claim 1, wherein: The telephoto projection optical system further includes an aperture stop, which is disposed between the fourth lens and the fifth lens.

3. The telephoto projection optical system according to claim 1, wherein: The telephoto projection optical system further includes an image biasing mirror and an illumination prism which are sequentially arranged between the tenth lens and the light valve from the object side to the image side.

4. The telephoto projection optical system according to claim 1, wherein: The second lens is cemented to the third lens, and the fifth lens, the sixth lens and the seventh lens are cemented to each other.

5. The telephoto projection optical system according to claim 1, wherein: The first lens is a concave-convex lens, and its object side surface is convex; The second lens is a biconcave lens; The third lens is a biconvex lens; The fourth lens is a meniscus lens, and its object side surface is a convex surface; The fifth lens is a biconcave lens; The sixth lens is a biconvex lens; The seventh lens is a meniscus lens, and its object side surface is concave; The eighth lens is a meniscus lens, and its object side surface is concave; The ninth lens is a biconvex lens; The tenth lens is a biconvex lens.

6. The long focus projection optical system according to claim 5, characterized in that: 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, the focal length of the eighth lens is f8, the focal length of the ninth lens is f9, and the focal length of the tenth lens is f10, wherein: -60<f1<-10, -60<f2<-10, 10<f3<60, 10<f4<60, -60<f5<-1 0, 10<f6<60, -60<f7<-10, 10<f8<60, 10<f9<70, 10<f10<60.

7. The telephoto projection optical system according to claim 5, characterized in that: The refractive index of the first lens is n1, and the dispersion coefficient is v1; the refractive index of the second lens is n2, and the dispersion coefficient is v2; the refractive index of the third lens is n3, and the dispersion coefficient is v3; the focal refractive index of the fourth lens is n4, and the dispersion coefficient is v4; the refractive index of the fifth lens is n5, and the dispersion coefficient is v5; the refractive index of the sixth lens is n6, and the dispersion coefficient is v6; the refractive index of the seventh lens is n7, and the dispersion coefficient is v7; the refractive index of the eighth lens is n8, and the dispersion coefficient is v8; the refractive index of the ninth lens is n9, and the dispersion coefficient is v9; the refractive index of the tenth lens is n10, and the dispersion coefficient is v10, wherein: 1.40≤n1≤1.60, 1.60≤n2≤1.80, 1.70≤n3≤1.90, 1.80≤n4≤2.00, 1.50≤n5≤1.70, 1.50≤n6≤1.70, 1.70≤n7≤1.90, 1.50≤n8≤1.70, 1.70≤n9≤1.90, 1.70≤n10≤1.90, 50.0≤v1≤70.0, 20.0≤v2≤40.0, 30.0≤v3≤50.0, 20.0≤v4≤40.0, 20.0≤v5≤40.0, 40.0≤v6≤90.0, 20.0≤v7≤40.0, 40.0≤v8≤90.0, 40.0≤v9≤60.0, 40.0≤v10≤60.

0.

8. The long focus projection optical system according to claim 1, wherein: The distance from the tenth lens to the light valve is BFL, and the total optical length of the telephoto projection optical system is TTL, wherein: 0.05<BFL / TTL<1.

9. The telephoto projection optical system according to claim 1, wherein: The total optical length of the telephoto projection optical system is TTL, the diameter of the first lens is D1, and the image plane diameter of the telephoto projection optical system is IC, wherein: 50mm<TTL<60mm, D1<27mm, IC≤15.8mm.

10. A projection device, characterized in that: Comprising the long-focus projection optical system as described in any one of claims 1 to 9.

Images