Optical lens with long projection ratio

Abstract

The invention relates to the technical field of projection optical lenses, and discloses an optical lens with a long projection ratio. From an object side to an image side along an optical axis: a light valve; the two sides of the first lens are convex surfaces; the triplet lens group is provided with a biconvex surface-biconcave surface-biconvex surface structure; the two sides of the fifth lens are convex surfaces and are spherical surfaces; the object side of the sixth lens is a concave surface, and the image side of the sixth lens is a convex surface; a diaphragm is arranged between the triplet lens and the fifth lens; the first lens, the triplet lens group and the fifth lens are made of glass materials, and the sixth lens is made of plastic materials. The chromatic aberration is corrected through the triplet lens group with the biconvex-biconcave-biconvex structure, and the resolution of an imaging result is improved. The glass spherical surface with the double-convex first lens is used for controlling high-temperature deformation of the lenses, and the plastic aspheric sixth lens is used for correcting spherical aberration, coordinating and simplifying an optical path, remarkably reducing the number of the lenses, avoiding stray light interference and energy loss caused by optical path redundancy, and having a long projection ratio and high resolution.

Description

Technical Field

[0001] The present invention relates to the technical field of projection optical lenses, and particularly to a long projection ratio optical lens. Background Art

[0002] In recent years, with the rapid development of ultra-high-definition image acquisition, intelligent visual perception, and immersive display technologies, the optical lens industry has faced increasingly stringent performance requirements. In the field of industrial precision inspection, the demand for micron-level defect recognition has driven the optical resolution to approach the physical limit; in the field of consumer electronics, virtual reality devices and ultra-thin projection devices have set higher standards for the compactness and long projection ratio of optical systems. This synchronous pursuit of high resolution and long projection ratio has become the core contradiction restricting the development of the new generation of optical systems.

[0003] In traditional optical design theory, to achieve high-resolution goals, long projection ratio lenses usually rely on the technical path of increasing the number of lenses and the complexity of lens groups. Although the stacked design of multiple lenses can compensate for aberrations and improve imaging quality to a certain extent, it inevitably leads to a significant extension of the optical path propagation path, resulting in increased light energy loss and doubled stray light interference. More prominently, the cumulative effect of the tolerance chain brought by multiple lens groups has exponentially increased the precision requirements of the assembly process, directly leading to high production and manufacturing costs.

[0004] Therefore, there is an urgent need for a long projection ratio optical lens that can maintain high resolution, long projection ratio, and reduce production costs. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a long projection ratio optical lens, which sequentially includes, from the object side to the image side along the optical axis: A light valve; A first lens with convex surfaces on both the object side and the image side; A three-glued lens group having a double-convex - double-concave - double-convex structure; A fifth lens with convex spherical surfaces on both the object side and the image side; A sixth lens with a concave object side and a convex image side; A diaphragm is arranged between the three-glued lens and the fifth lens; Wherein the first lens, the three-glued lens group, and the fifth lens are made of glass, and the sixth lens is made of plastic.

[0006] Further, the first lens has a positive optical power.

[0007] Further, the refractive index of the first lens is [1.44, 1.54].

[0008] Further, along the optical axis, the three-glued lens group sequentially includes: A second lens with convex surfaces on both the object side and the image side; A third lens with concave surfaces on both the object side and the image side; A fourth lens with convex surfaces on both the object side and the image side.

[0009] Furthermore, the second lens, the third lens, and the fourth lens are all set with negative optical powers; The Abbe numbers of the second lens and the fourth lens are in the range of [75, 85]; The Abbe number of the third lens is in the range of [25, 35], and the refractive index is in the range of [1.80, 1.90].

[0010] Furthermore, the fifth lens is set with a positive optical power; The refractive index of the fifth lens is in the range of [1.80, 1.90], and the Abbe number is in the range of [18, 28].

[0011] Furthermore, the sixth lens is set with a negative optical power.

[0012] Furthermore, the refractive index of the sixth lens is in the range of [1.48, 1.58], and the Abbe number is in the range of [50, 60].

[0013] Furthermore, the distance from the plane where the light valve is located to the vertex on the object side of the first lens is denoted as BFL, and the distance from the vertex on the object side of the first lens to the vertex on the image side of the sixth lens is denoted as L; Where 0.5 < BFL / L < 1.

[0014] Furthermore, the equivalent focal length of the lens group is denoted as F1, the equivalent focal length of the first lens is denoted as F2, the equivalent focal length of the triplet lens group is denoted as F3, the equivalent focal length of the fifth lens is denoted as F4, and the equivalent focal length of the sixth lens is denoted as F5; Satisfy the conditional formula: 1 < |F2 / F1| < 3; 10 < |F3 / F1| < 15; 1 < |F4 / F1| < 5; 1 < |F5 / F1| < 2.

[0015] The embodiments of the present invention have the following technical effects: The optical lens provided by the present invention comprises, along the optical axis from the object side to the image side in sequence: a light valve; a first lens with convex surfaces on both the object side and the image side; a triplet lens group having a double-convex - double-concave - double-convex structure; a fifth lens with convex spherical surfaces on both the object side and the image side; a sixth lens with a concave object side and a convex image side; a diaphragm is disposed between the triplet lens and the fifth lens; wherein the first lens, the triplet lens group and the fifth lens are made of glass, and the sixth lens is made of plastic. By means of the triplet lens group having a double-convex - double-concave - double-convex structure, chromatic aberration is corrected, and the resolution of the imaging result is improved. Through the glass spherical surface of the double-convex first lens, the high-temperature deformation of the lens is controlled, and the aspherical plastic sixth lens is used to correct spherical aberration. Through their collaborative cooperation, the optical path is streamlined, the number of lenses is significantly reduced, the stray light interference and energy loss caused by redundant optical paths are avoided, and at the same time, the manufacturing cost is reduced, and both long projection ratio and high resolution are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 is a schematic structural diagram of the optical lens provided by an embodiment of the present invention; Figure 2 is a geometric MTF curve graph of the simulation design of the optical lens provided by an embodiment of the present invention; Figure 3 is an optical field curvature and distortion graph of the optical lens provided by an embodiment of the present invention; Figure 4 is a ray Ray Fan graph of the optical lens provided by an embodiment of the present invention; Figure 5 is a spot diagram of the point array spots under different field conditions on the imaging screen of the optical lens provided by an embodiment of the present invention; Figure 6 is a lateral chromatic aberration graph of the optical lens provided by an embodiment of the present invention; Figure 7 is a defocus geometric MTF graph of the optical lens provided by an embodiment of the present invention; Figure 8 is a simple simulation projection diagram of the optical lens provided by an embodiment of the present invention.

[0018] 1. Light valve; 2. Prism; 3. Second protective glass; 4. First lens; 5. Second lens; 6. Third lens; 7. Fourth lens; 8. Diaphragm; 9. Fifth lens; 10. Sixth lens. Detailed implementation manners

[0019] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part rather than all of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope protected by the present invention.

[0020] Traditional long projection ratio lenses usually adopt a multi-lens stacking design to achieve high resolution, resulting in: Optical path redundancy: The optical path propagation path is extended, the interference of stray light is aggravated, and the light energy loss is significantly increased; Tolerance sensitivity: The cumulative effect of the tolerance chain of the lens group is amplified, the assembly accuracy requirement increases steeply, and the yield rate decreases; Cost pressure: The processing of high-precision aspherical surfaces and the complexity of the multi-lens assembly process are increased, and the manufacturing cost is difficult to control. Based on this, the present invention provides a long projection ratio optical lens. Figure 1 It is a schematic structural diagram of the optical lens provided by the embodiment of the present invention. As Figure 1 shown, the optical lens provided by the present invention, from the object side to the image side along the optical axis, is successively: Light valve 1; used to provide a high-resolution image beam.

[0021] Exemplarily, the light valve 1 is a DMD chip or an LCos chip. The light valve 1 is a light modulation element, and the universality of the lens is relatively high. There is also a TIR total reflection prism 2 between the light valve 1 and the first lens 4, which is used to reflect the imaging picture, effectively reducing the volume of the lens optical machine. The second protective glass 3 is used to protect the relatively fragile glass aspherical lens of the first lens 4, preventing dust and damage.

[0022] Exemplarily, a first protective glass ( Figure 1 the reference numeral is not shown in the figure), a prism 2 and a second protective glass 3 can also be successively arranged between the light valve 1 and the first lens 4; The prism 2 is used to reflect the imaging picture, and the first protective glass is respectively used to protect the prism 2..

[0023] The first lens 4 with convex surfaces on both the object side and the image side; In some embodiments, the first lens 4 has a positive optical power.

[0024] In some embodiments, the refractive index of the first lens 4 is [1.44, 1.54].

[0025] Exemplarily, the surface shape of the first lens 4 is a glass-molded aspherical biconvex lens. The material is D-FK61, which has a positive optical power distribution. This lens has low dispersion characteristics, can significantly reduce chromatic aberration (especially longitudinal chromatic aberration), and improve the color reproduction of the projection image. In the visible light band (370 - 780 nm), the refraction differences of light rays with different wavelengths are effectively suppressed, avoiding image blurring caused by marginal dispersion. Preferably, the refractive index of the first lens 4 is set to 1.49, which belongs to medium-refractive-index glass. Combining with the positive optical power distribution, it can not only achieve moderate convergence of light rays but also control the lens thickness, avoiding marginal aberrations (such as field curvature and distortion) caused by high refractive index. The glass material has a low coefficient of thermal expansion and stable chemical properties, and is not easily deformed in a high-temperature environment (such as near the DMD chip), which can avoid image plane shift (focus shift) caused by thermal expansion and contraction. The aspherical design can effectively eliminate spherical aberration, and through positive optical power distribution and optical path optimization, it can compensate for some aberrations (such as coma and astigmatism), especially suitable for this small-aperture (optical system F / # is 1.7), short-back-focus DMD optical path structure (the back working distance is 12 mm). The glass material has a high hardness (Mohs hardness ≥ 6), better wear resistance than resin materials, and is not easily scratched during long-term use, suitable for the stringent environmental requirements of high-precision projection systems (such as laser projection). The medium-refractive-index glass has a relatively low density (about 2.5 g / cm³), which reduces the lens weight while ensuring optical performance, facilitating the structural design of compact projectors.

[0026] A triplet lens group having a biconvex - biconcave - biconvex structure; In some embodiments, along the optical axis, the triplet lens group sequentially includes: A second lens 5 with convex surfaces on both the object side and the image side; A third lens 6 with concave surfaces on both the object side and the image side; A fourth lens 7 with convex surfaces on both the object side and the image side.

[0027] In some embodiments, the second lens 5, the third lens 6, and the fourth lens 7 are all set with negative optical powers; The Abbe numbers of the second lens 5 and the fourth lens 7 are in the range of [75, 85]; The Abbe number of the third lens 6 is in the range of [25, 35], and the refractive index is in the range of [1.80, 1.90].

[0028] Exemplarily, the second lens 5, the third lens 6 and the fourth lens 7 form a triple cemented lens. The second lens 5 and the fourth lens 7 are made of material H-FK61 and both are assigned positive optical powers. The third lens 6 is made of material H-ZLAF76A and is assigned negative optical power. Preferably, the second lens 5 and the fourth lens 7 are made of H-FK61 (high Abbe number): with an Abbe number of 81 and low dispersion coefficient, which is used to suppress chromatic aberration, especially secondary spectrum. Preferably, the third lens 6 is made of H-ZLAF76A (low Abbe number): with an Abbe number of 30 and high refractive index (1.85), forming a refractive index difference with H-FK61, compensating for axial chromatic aberration through positive-negative-positive optical power distribution, and reducing the focus separation of red and blue light. This combination can significantly reduce spherical aberration, achieve chromatic aberration balance in a wide wavelength band (such as visible light), and avoid color fringing at the edges of the projected image. The optical power distribution of the triple cemented lens is double convex (positive)-double concave (negative)-double convex (positive). The outer double convex lenses (H-FK61) provide the main focusing ability. The middle double concave lens (H-ZLAF76A) introduces negative optical power to offset spherical aberration and field curvature. The last double convex lens (H-FK61) balances the overall optical path and suppresses higher-order astigmatism and coma. The overall negative optical power is concentrated. The middle negative lens enhances the optical power contribution through a high refractive index material, without significantly increasing the lens thickness, reducing the system complexity. It can reduce the RMS spot radius of the full field of view, improve the imaging uniformity of the DMD chip, and meet the high-resolution requirements of small-sized chips (such as 0.16 inches). The thermal expansion difference between H-FK61 (low thermal expansion coefficient) and H-ZLAF76A (medium thermal expansion coefficient) is compensated by the cementing process, reducing the lens stress deformation caused by temperature changes and suppressing thermal defocusing. In the assembly, the triple cemented structure cures tolerance-sensitive parameters (such as curvature error, eccentricity) through the adhesive layer, reducing the assembly difficulty and adapting to the high-frequency vibration environment of the projector. The high refractive index H-ZLAF76A (1.85) allows the middle negative lens to have a smaller curvature radius, shortening the total length of the lens group (the total length of a typical case is 44 mm, F number is 1.7), meeting the requirements of miniaturization and thinness of the micro-projector. The double convex-double concave-double convex symmetric layout optimizes the chief ray angle, reduces the deflection of the incident light on the DMD chip after the prism 2, and reduces the risk of stray light.

[0029] A fifth lens 9 with convex surfaces on both the object side and the image side and being spherical; In some embodiments, the fifth lens 9 is assigned positive optical power; The refractive index of the fifth lens 9 is in the range of [1.80, 1.90], and the Abbe number is in the range of [18, 28].

[0030] Exemplarily, the fifth lens 9 is made of material H-ZF52, has a positive optical power, and a double-convex glass spherical surface. Preferably, the fifth lens 9 is made of H-ZF52 with a high refractive index (1.84). Without the need to achieve a stronger light deflection ability through a steeper radius of curvature, the number of lenses or the thickness can be reduced, which helps to miniaturize the system. The low Abbe number (23) is set as a high-dispersion glass. When combined with a low-dispersion material (such as D-FK61), axial chromatic aberration and lateral chromatic aberration can be significantly suppressed, especially suitable for DMD projection systems with multi-wavelength light sources. The double-convex structure can balance spherical aberration and coma near the aperture stop 8, reduce spot diffusion, and improve the MTF contrast. When arranged closely to the aperture stop 8, it can effectively constrain the chief ray angle and reduce astigmatism and distortion in the marginal field of view (<0.3% distortion requirement). The combination of high refractive index and low Abbe number can offset the dispersion effect of the reflection optical path of the DMD chip, reduce the separation of red, green, and blue colors (rainbow effect), and meet the stringent requirements of DMD projectors for color reproduction. The double-convex lens is less sensitive to the curvature radius error. Combined with the low thermal expansion coefficient of H-ZF23 glass, the influence of temperature drift on the focal plane shift can be reduced. The sixth lens 10 with a concave object side and a convex image side; An aperture stop 8 is arranged between the triplet lens and the fifth lens 9; it constrains the chief ray angle, reduces astigmatism in the marginal field of view, and optimizes the optical path propagation path to shorten the total length of the system.

[0031] In some embodiments, the sixth lens 10 has a negative optical power.

[0032] In some embodiments, the refractive index of the sixth lens 10 is in the range of [1.48, 1.58], and the Abbe number is in the range of [50, 60].

[0033] Exemplarily, the sixth lens 10 is a convex-concave lens that assigns negative optical power. It is located at the exit pupil opening, made of plastic material K26R, and is the farthest from the light valve 1. Its surface is a plastic aspheric surface, and the surface continuously changes through curvature, which can correct monochromatic aberrations such as spherical aberration and coma, especially higher-order aberrations (such as third-order spherical aberration). Compared with traditional spherical lenses, its spot concentration is higher, and the resolution of the edge field of view is significantly improved. The combination of convex-concave aspheric surface and negative optical power distribution can compensate for system distortion (such as barrel / pincushion distortion), making the geometric distortion of the projection image <0.3%, meeting the requirements of high-precision image restoration. Preferably, the sixth lens 10 is made of K26 material, and its Abbe number (55) is between low dispersion and conventional glass. Combined with negative optical power distribution, it can balance lateral chromatic aberration (such as magnification chromatic aberration) and axial chromatic aberration, reducing multi-wavelength spot separation. Setting the refractive index of 1.53 to form a gradient combination with the material of the front lens group (such as D-FK61-25, H-ZLAF76A) can optimize the optical power distribution, reduce the system sensitivity, and improve the tolerance robustness. The plastic aspheric lens is 30% - 50% lighter than the glass material, and the injection molding process reduces the processing cost, making it suitable for large-scale production of consumer-grade projection lenses. The tolerance requirements for the radius of curvature and thickness can be relaxed (such as ±0.05mm), reducing the assembly difficulty and improving the yield. The thermal expansion coefficient (CTE) of the plastic material has better compatibility with the metal lens barrel, reducing the defocus problem caused by temperature drift, and is suitable for high-power LED / LD light source scenarios. The convex-concave negative optical power lens can shorten the back focal distance and support the miniaturized design of the ultra-short focal projection system.

[0034] Wherein the first lens 4, the triplet lens group, and the fifth lens 9 are made of glass material, and the sixth lens 10 is made of plastic material.

[0035] The solution of the present invention can achieve high-resolution projection imaging quality under long projection ratio conditions without adjusting the focal length, by changing the projection distance and using a very small number of lens refraction systems.

[0036] In some embodiments, the distance from the plane where the light valve 1 is located to the object-side vertex of the first lens 4 is denoted as BFL, and the distance from the object-side vertex of the first lens 4 to the image-side vertex of the sixth lens 10 is denoted as L; Where 0.5 < BFL / L < 1.

[0037] In some embodiments, the equivalent focal length of the lens group is denoted as F1, the equivalent focal length of the first lens 4 is denoted as F2, the equivalent focal length of the triplet lens group is denoted as F3, the equivalent focal length of the fifth lens 9 is denoted as F4, and the equivalent focal length of the sixth lens 10 is denoted as F5; Satisfy the conditional formula: 1 < |F2 / F1| < 3; 10 < |F3 / F1| < 15; 1 < | F4 / F1 | < 5; 1 < | F5 / F1 | < 2.

[0038] This optical lens does not require a focusing design and only adopts a fixed focal length design, which can automatically maintain clear imaging at different projection distances, avoiding the cumbersome operation of frequent manual focusing required by traditional projectors due to distance changes. Users only need to move the position of the projector to adjust the screen size (such as 20 - 120 inches), without the need for professional calibration, and it is suitable for scenarios such as temporary meetings and outdoor activities. The same lens can cover the needs from small-sized home audio and video (20 inches) to large conference rooms / classrooms (120 inches), reducing the equipment replacement cost. The long projection ratio (1.2 - 1.5) allows for large-screen projection at a long distance, avoiding the problem that the lens cannot expand the screen size due to space limitations, especially suitable for large spaces such as exhibition halls and auditoriums. The fixed focus design reduces the wear of the lens components, and only requires regular cleaning of the lens, making it suitable for high-frequency use.

[0039] Figure 2 It is the geometric MTF curve graph of the simulation design of the optical lens provided by the embodiment of the present invention. The maximum value of the ordinate after normalization calculation is 1, representing the resolution ability. The higher the value of the ordinate, the stronger the resolution ability and the higher the reduction degree of the image quality. The unit of the abscissa is cycle / mm (lp / mm). This projection lens is adapted to a 0.16-inch DMD chip, and the pixel size of the reference DMD specification is 5.4μm. According to the calculation formula: , the reference value of the cut-off frequency is calculated to be 93 lp / mm, and the geometric MTF value at the 93 lp / mm cut-off frequency is greater than 0.6, meeting the characteristics of high resolution.

[0040] Figure 3 It is the optical field curvature and distortion graph of the optical lens provided by the embodiment of the present invention. The maximum field curvature of this optical system is less than 0.07 mm (as shown in the left figure of Figure 3 ), and the maximum optical distortion is less than 0.3% (as shown in the right figure of Figure 3 ). This optical system performs excellently in terms of distortion and field curvature, meeting the high-precision requirements.

[0041] Figure 4 It is the ray Ray Fan graph (ray fan graph) of the optical lens provided by the embodiment of the present invention. The abscissa is the normalized pupil position (-1 to +1), and the ordinate is the height difference (unit: micrometer) between the ray and the chief ray on the image plane. The blue is the light with a wavelength of 0.456 mm, the green is the light with a wavelength of 0.515 mm, and the red is the light with a wavelength of 0.617 mm. The slope near the origin of this graph is close to 0, indicating good spherical aberration correction. The slope difference between the meridional and sagittal curves is not obvious, the astigmatism phenomenon is not prominent, the meridional direction has a relatively small parabolic slope, and the coma image is small. It can be concluded that the aberration of this system is within an acceptable range.

[0042] Figure 5 It is the spot diagram of point arrays on the imaging screen of the optical lens provided by the embodiments of the present invention under different field conditions. The figure shows the schematic diagram of the spot imaging of three different wavelength lights (0.45um, 0.55um, 0.62um) on the screen under a certain field condition on the premise of normalized different field conditions. Among them, the RMS radius values corresponding to the actual image plane field distribution from low to high are: 1.799, 2.197, 1.869, 1.702, 1.612, 1.570, 1.717, 1.857, 1.894, 1.821, and the corresponding GEO radius values are 4.112, 8.085, 8.242, 6.974, 4.239, 3.966, 4.063, 4.582, 5.07, 4.911. It satisfies GEO < 5×RMS, indicating that the spot energy is relatively concentrated, and the interference of marginal rays on imaging is significantly reduced.

[0043] Figure 6 It is the lateral chromatic aberration diagram of the optical lens provided by the embodiments of the present invention. By comparing the lateral offsets of different wavelengths (such as F, d, and C lights) on the image plane, the magnitude and direction of the lateral chromatic aberration are intuitively displayed. The system effectively corrects chromatic aberration using a triplet lens. The offset of the lateral chromatic aberration is significantly less than 1.2μm, which is significantly less than the size of the Airy disk radius, indicating that the system performs excellently in terms of chromatic aberration correction, diffraction-limited performance, and tolerance robustness, and is suitable for optical design scenarios with strict requirements for resolution and geometric fidelity.

[0044] Figure 7 It is the defocus geometric MTF diagram of the optical lens provided by the embodiments of the present invention (corresponding to 20 inch, 40 inch, and 120 inch imaging screens), indicating that the lens has a wide depth of focus tolerance within the defocus range (for example, the depth of focus with MTF≥0.3 ≥ 0.02mm). Even when the screen size changes significantly (such as expanding from 20 inches to 120 inches), high contrast and resolution can be maintained without focusing, reducing the operation complexity. Higher-order aberrations (such as spherical aberration and field curvature) are effectively suppressed, and the gentle attenuation of the MTF curve under different defocus states (such as the slope difference of the 20 - 40 lp / mm curve < 5%) ensures the image quality uniformity from the center to the edge, avoiding visual distortion caused by local blurring in large-size screens.

[0045] Figure 8 It is a simple diagram of the simulated projection of the optical lens provided by the embodiments of the present invention. The projection screen Offset corresponding to the projection lens of the present invention is 100%. When the projection distances are 0.53 m, 1.06m, and 3.18m respectively, they correspond to 20inch, 40inch, and 120inch screens. According to the formula: , the projection ratio ranges between 1.2 and 1.5, meeting the characteristics of a long projection ratio for the optical lens.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A long throw ratio optical lens, characterized in that: Along the optical axis from the object side to the image side: Light valve (1); A first lens (4) having convex surfaces on both the object side and the image side; A triplet lens group having a biconvex-biconcave-biconvex structure; A fifth lens (9) having convex spherical surfaces on both the object side and the image side; a sixth lens (10) having a concave surface on the object side and a convex surface on the image side; An aperture stop (8) is provided between the triplet lens and the fifth lens (9); The first lens (4), the triplet lens group and the fifth lens (9) are made of glass, and the sixth lens (10) is made of plastic.

2. The long throw ratio optical lens according to claim 1, characterized in that: The first lens (4) has positive optical power.

3. The long throw ratio optical lens according to claim 2, characterized in that: The refractive index of the first lens (4) is [1.44, 1.54].

4. The long throw ratio optical lens according to claim 1, characterized in that: The three-cemented lens group along the optical axis includes: A second lens (5) having convex surfaces on both the object side and the image side; A third lens (6) having concave surfaces on both the object side and the image side; The fourth lens (7) has convex surfaces on both the object side and the image side.

5. The long throw ratio optical lens according to claim 4, characterized in that: The second lens (5), the third lens (6) and the fourth lens (7) are all set with negative optical power; The Abbe numbers of the second lens (5) and the fourth lens (7) are [75, 85]; The Abbe number of the third lens (6) is [25, 35], and the refractive index is [1.80, 1.90].

6. The long throw ratio optical lens according to claim 1, characterized in that: The fifth lens (9) is provided with positive focal power; The refractive index of the fifth lens (9) is [1.80, 1.90], and the Abbe number is [18, 28].

7. The long throw ratio optical lens according to claim 1, characterized in that: The sixth lens (10) is provided with negative optical power.

8. The long throw ratio optical lens according to claim 7, characterized in that: The refractive index of the sixth lens (10) is [1.48, 1.58], and the Abbe number is [50, 60].

9. The long throw ratio optical lens according to claim 1, characterized in that: The distance from the surface where the light valve (1) is located to the object side vertex of the first lens (4) is recorded as BFL, and the distance from the object side vertex of the first lens (4) to the image side vertex of the sixth lens (10) is recorded as L; Where 0.5< BFL / L < 1.

10. The long throw ratio optical lens according to claim 9, characterized in that: The equivalent focal length of the lens group is recorded as F1, the equivalent focal length of the first lens (4) is recorded as F2, the equivalent focal length of the triplet lens group is recorded as F3, the equivalent focal length of the fifth lens (9) is recorded as F4, and the equivalent focal length of the sixth lens (10) is recorded as F5; Satisfy the condition: 1< | F2 / F1 | < 3; 10 < | F3 / F1 | < 15; 1<|F4 / F1|<5; 1< | F5 / F1 | < 2.

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