A broadband imaging lens
By combining positive diopter glass spherical lenses and cemented doublet lens design, along with aluminum spacers and aperture optimization, the problem of poor imaging quality in the miniaturization process of broadband lenses has been solved, resulting in a lightweight, low-cost, and high-quality broadband imaging lens.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- XIAMEN LEADING OPTICS
- Filing Date
- 2025-06-23
- Publication Date
- 2026-05-26
AI Technical Summary
Existing broadband lenses struggle to balance broadband spectrum with image quality in the pursuit of miniaturization, posing challenges to optical system design.
It employs a positive diopter glass spherical lens combination design, combined with cemented doublet lenses, aluminum spacers and SOMA plates, to optimize the light path. Through aperture position adjustment and sealing ring design, it ensures uniform light convergence and prevents stray light, achieving high image quality.
It achieves a lightweight, compact, and low-cost broadband imaging lens weighing less than 100 grams, with a center MTF of 32lp/mm > 0.5 and an edge MTF of 32lp/mm > 0.3. It also features IP68 waterproof and dustproof rating and high image quality.
Smart Images
Figure CN224287235U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of spectral lens technology, and in particular to a broadband imaging lens. Background Technology
[0002] Broadband lenses are widely used in many fields, such as satellite remote sensing imaging, day and night imaging monitoring, and forest fire monitoring. To meet the requirements of the lens installation environment and to acquire information about objects invisible in the visible light band, lenses are required to be small, lightweight, and have a wide spectrum. However, the design of existing broadband lenses often faces a technical bottleneck: in the pursuit of miniaturization, it is difficult to balance wide spectrum and image quality. This contradiction poses a greater challenge to the design of optical systems, requiring breakthroughs in areas such as optical power allocation and structural optimization to meet the requirements of broadband lenses for different application scenarios. Utility Model Content
[0003] In view of this, the purpose of this utility model is to provide a broadband imaging lens. This lens can at least solve one of the technical shortcomings mentioned in the background art.
[0004] According to one aspect of the present invention, a broadband imaging lens is provided, comprising a lens group disposed inside the lens barrel, wherein the lens group is provided with a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens in sequence along the optical axis from the object plane to the image plane; the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical lenses and all have positive refractive power;
[0005] The object-side surface of the first lens is convex, and the image-side surface is concave.
[0006] The object-side surface of the second lens is convex, and the image-side surface is concave.
[0007] The object-side surface of the third lens is convex, and the image-side surface is concave.
[0008] The object-side surface of the fourth lens is convex, and the image-side surface is concave.
[0009] The object-side surface and the image-side surface of the fifth lens are both convex.
[0010] The object side and image side of the sixth lens are both concave.
[0011] In some embodiments, the third lens and the fourth lens are both cemented glass lenses.
[0012] In some embodiments, a first aluminum spacer is provided between the second lens and the third lens; a second aluminum spacer is provided between the third lens and the fourth lens; and a third aluminum spacer is provided between the fifth lens and the sixth lens.
[0013] In some embodiments, a first SOMA sheet is provided between the third lens and the second aluminum spacer ring, a second SOMA sheet is provided between the image side of the fourth lens and the lens barrel, and a third SOMA sheet is provided between the third aluminum spacer ring and the sixth lens.
[0014] In some embodiments, the aperture stop is arranged between the second lens and the third lens, and the aperture stop is located on the object side surface of the third lens.
[0015] In some embodiments, a first aluminum press ring is provided on the object surface of the first lens, a second aluminum press ring is provided on the object surface of the second lens, and a third aluminum press ring is provided on the image surface of the sixth lens. The first aluminum press ring, the second aluminum press ring, and the third aluminum press ring are fixed to the inner wall of the lens barrel by dispensing glue.
[0016] In some embodiments, a sealing ring is provided between the first lens and the aluminum lens barrel.
[0017] In some embodiments, extinction patterns are provided on the inner wall of the aluminum lens barrel between the first lens and the second lens, the third lens and the fourth lens; stepped inclined surfaces are provided on the object side of the first aluminum press ring and the second aluminum press ring and on the image side of the third aluminum press ring.
[0018] In some embodiments, the outer diameter of the front end of the lens is 45.98 mm < D1 < 46.01 mm, the tail is 22.98 mm < D2 < 23 mm, the total structural length is 53.17 mm < L1 < 53.23 mm, the EFL is 50 mm, and the weight is not more than 100 g.
[0019] In some embodiments, the spectral range of the lens is 400 - 1000 nm, the central MTF satisfies 32 lp / mm > 0.5, and the peripheral MTF satisfies 32 lp / mm > 0.3.
[0020] The beneficial effects of the present utility model are as follows: It provides a lens with an EFL of 50 mm, a spectral range of 400 - 1000 nm, a weight within 100 grams, a central MTF satisfying 32 lp / mm > 0.5, a peripheral MTF satisfying 32 lp / mm > 0.3, effectively avoiding stray light and ghost images caused by plane reflection, having high imaging quality, small volume, low cost, and the lens head also having the characteristics of IP68-level waterproof and dustproof, wide application range of the product, and being conducive to promotion. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0022] Figure 1 This is a schematic diagram of the structure of a broadband imaging lens according to the present invention;
[0023] Figure 2 This is an MTF curve of a broadband imaging lens according to this utility model;
[0024] Figure 3 This is a field curvature and distortion curve diagram of Example 1 of a broadband imaging lens of this utility model.
[0025] Figure label:
[0026] 1: First lens; 2: Second lens; 3: Third lens; 4: Fourth lens; 5: Fifth lens; 6: Sixth lens; 7: Lens barrel; 8: First aluminum pressure ring; 9: Sealing ring; 10: Second aluminum pressure ring; 11: First aluminum spacer; 12: First SOMA sheet; 13: Second aluminum spacer; 14: Second SOMA sheet; 15: Third aluminum spacer; 16: Third SOMA sheet; 17: Third aluminum pressure ring; 18: Matte finish; 19: Stepped slope. Detailed Implementation
[0027] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are only for illustrating the present invention and do not limit the scope of the present invention. Similarly, the following embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.
[0028] The purpose of this invention is to provide a broadband imaging lens with high optical performance. Embodiments according to this invention will now be described in detail with reference to the accompanying drawings.
[0029] Figure 1 This is a cross-sectional view of a lens (optical system). Lenses are used in equipment including satellite remote sensing imaging, day and night imaging monitoring, forest fire monitoring, and interchangeable-lens optical devices. In the cross-sectional view, the left side is the object-side OBJ, and the right side is the image-side IMA, with the optical axis OA.
[0030] According to the broadband imaging lens, in order from the object side to the image side, it includes: a broadband imaging lens, comprising a lens group disposed inside the lens barrel 7, wherein the lens group is provided with a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, and a sixth lens 6 in sequence along the optical axis from the object plane to the image plane; the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are all glass spherical lenses and all have positive refractive power;
[0031] The object side of the first lens 1 is convex, and the image side is concave.
[0032] The object side of the second lens 2 is convex, and the image side is concave.
[0033] The object side of the third lens 3 is convex, and the image side is concave.
[0034] The object-side surface of the fourth lens 4 is convex, and the image-side surface is concave.
[0035] The object-side surface and the image-side surface of the fifth lens 5 are both convex.
[0036] The object side and image side of the sixth lens 6 are both concave.
[0037] In the above technical solution, through the optimized design of the above technical solution, the broadband imaging lens simplifies the optical path of the lens and reduces the reflection loss of light between the lenses by using a combination design of glass spherical lenses with positive diopter. This enables the modified spectral lens to meet the design requirements of EFL 50mm, spectral range of 400-1000nm, weight of less than 100 grams, center MTF of 32lp / mm>0.5, edge MTF of 32lp / mm>0.3, high imaging quality, wide spectral range, small size and low cost.
[0038] Furthermore, both the third lens 3 and the fourth lens 4 are cemented glass lenses.
[0039] In the aforementioned technical solution, by designing the third lens 3 and the fourth lens 4 as a cemented doublet, and setting both the object-side surfaces of the third lens 3 and the fourth lens 4 to be convex and the image-side surfaces to be concave, this technical solution exhibits significant advantages in collimation and optimization of the light convergence path, providing an efficient optical solution for broadband imaging lenses. Specifically, the cemented doublet, by cementing two lenses of different optical materials together, utilizes their dispersion characteristics to compensate for each other, effectively eliminating chromatic aberration while significantly reducing aberrations such as spherical aberration, field curvature, and astigmatism. This design allows light from different spectra to converge more uniformly onto the imaging plane, thereby improving the overall image quality. On the other hand, it helps optimize the light deflection path, enabling incident beams from each field of view to converge more precisely onto the imaging plane after passing through the optical system. This design not only improves image sharpness but also enhances the system's optical transfer function (MTF) performance, ensuring excellent image quality even at high resolution. The cemented doublet design, while maintaining the compactness of the optical system, provides sufficient degrees of freedom to balance and correct various aberrations. This structure optimizes the optical power distribution of the system, enabling the optical system to achieve higher performance within a limited physical size.
[0040] Furthermore, a first aluminum spacer 11 is provided between the second lens 2 and the third lens 3; a second aluminum spacer 13 is provided between the third lens 3 and the fourth lens 4; and a third aluminum spacer 15 is provided between the fifth lens 5 and the sixth lens 6.
[0041] Furthermore, a first SOMA sheet 12 is provided between the third lens 3 and the second aluminum spacer 11, a second SOMA sheet 14 is provided between the image side of the fourth lens 4 and the lens barrel 7, and a third SOMA sheet 16 is provided between the third aluminum spacer 15 and the sixth lens 6. By providing SOMA sheets at these positions, light reflection can be prevented, avoiding stray light.
[0042] Furthermore, the aperture stop is positioned between the second lens 2 and the third lens 3, with the aperture stop located on the surface of the object measurement surface of the third lens 3.
[0043] In the above technical solution, by placing an aperture stop between the second lens and the third lens 3, effective correction of optical system aberrations is achieved, significantly improving image quality. Specifically, by adjusting the distance between the aperture stop and the lens group, the focusing characteristics of light in the optical system are optimized. This design is particularly helpful in compensating for coma, that is, the difference in focusing of light between the lens edge and the center, thereby improving the system's imaging sharpness. At the same time, optimizing the position of the aperture stop also helps reduce system distortion, ensuring that the geometry of the image remains true.
[0044] Further, a first aluminum alloy retaining ring 8 is provided on the object surface of the first lens 1, a second aluminum alloy retaining ring 10 is provided on the object surface of the second lens 2, and a third aluminum alloy retaining ring 17 is provided on the image surface of the sixth lens 6. The first aluminum alloy retaining ring 8, the second aluminum alloy retaining ring 10, and the third aluminum alloy retaining ring 17 are fixed to the inner wall of the lens barrel 7 by dispensing glue.
[0045] In the above technical solution, the distance between the first lens 1 and the second lens 2 is too large. If a metal spacer is used, it will increase the cost and weight of the lens. Therefore, the second lens 2 to the fourth lens 4 are fixed by retaining rings, effectively reducing the weight of the lens.
[0046] Further, a sealing ring 9 is provided between the first lens 1 and the aluminum alloy lens barrel 7.
[0047] In the above technical solution, the main purpose of the sealing ring 9 is to attach a rubber sealing ring 9 here, enabling the lens to have the functions of IP68-level waterproof and dustproof.
[0048] Further, extinction patterns 18 are provided on the inner wall of the aluminum alloy lens barrel 7 between the first lens 1 and the second lens 2, the third lens 3 and the fourth lens 4; stepped inclined surfaces 19 are provided on the object sides of the first aluminum alloy retaining ring 8 and the second aluminum alloy retaining ring 10 and the image side of the third aluminum alloy retaining ring 17.
[0049] In the above technical solution, the purpose is that the stepped inclined surfaces 19 and the extinction patterns 18 of the retaining rings that are close to parallel with the light are effective in preventing stray light and ghost images in the lens caused by plane reflection.
[0050] Further, for the lens, the outer diameter at the front end is 45.98mm < D1 < 46.01mm, the tail is 22.98mm < D2 < 23mm, the overall structural length is 53.17mm < L1 < 53.23mm, the EFL is 50mm, and the weight is not greater than 100g.
[0051] In the above technical solution, by reasonably controlling the overall length and effective focal length (EFL) of the lens, the best balance between the volume and imaging quality of the optical system is ensured. Specifically: when the overall length and effective focal length of the lens are controlled within the above numerical ranges, the optical system can ensure excellent imaging quality while maintaining a small volume. This design avoids the decrease in imaging quality caused by too small volume and the unsatisfactory miniaturization caused by too large volume by precisely controlling the compactness of the optical system. When the overall length of the lens is too large, the volume of the optical system may be too small, resulting in limited light paths and affecting imaging quality. When the overall structural length of the lens is 53.17mm < L1 < 53.23mm, the optical system can achieve the best light power distribution and aberration correction within a limited volume, ensuring that the imaging quality is not affected. When the overall length of the lens is too small, the volume of the optical system may be too large, increasing the manufacturing cost and portability problems, and may also lead to redundancy in optical performance.
[0052] Furthermore, the lens has a spectral range of 400–1000 nm, a center MTF of 32 lp / mm > 0.5, and an edge MTF of 32 lp / mm > 0.3, thus exhibiting good imaging quality.
[0053] Although the present invention has been described with reference to exemplary embodiments, it should be understood that the present invention is not limited to the disclosed exemplary embodiments. The scope of the following claims will be given the broadest interpretation to cover all such modifications and equivalent structures and functions.
Claims
1. A broadband imaging lens, characterized in that, It includes a lens group arranged inside the lens barrel. The lens group successively has a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens along the optical axis from the object surface to the image surface; the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all glass spherical lenses and all have positive refractive powers; The object side surface of the first lens is convex and the image side surface is concave; The object side surface of the second lens is convex and the image side surface is concave; The object side surface of the third lens is convex and the image side surface is concave; The object side surface of the fourth lens is convex and the image side surface is concave; The object side surface of the fifth lens is convex and the image side surface is convex; The object side surface of the sixth lens is concave and the image side surface is concave; There are light extinction patterns on the inner wall of the aluminum lens barrel between the first lens and the second lens, and between the third lens and the fourth lens; a first aluminum press ring is provided on the object surface of the first lens, a second aluminum press ring is provided on the object surface of the second lens, and a third aluminum press ring is provided on the image surface of the sixth lens. There are stepped inclined surfaces on the object side of the first aluminum press ring and the second aluminum press ring and on the image side of the third aluminum press ring; the outer diameter at the front end of the lens is 45.98mm < D1 < 46.01mm, the tail is 22.98mm < D2 < 23mm, the total structural length is 53.17mm < L1 < 53.23mm, the EFL is 50mm, and the weight is not more than 100g.
2. A broadband imaging lens as described in claim 1, characterized in that, Both the third lens and the fourth lens are glass cemented lenses.
3. A broadband imaging lens as described in claim 1, characterized in that, A first aluminum spacer is provided between the second lens and the third lens; a second aluminum spacer is provided between the third lens and the fourth lens; a third aluminum spacer is provided between the fifth lens and the sixth lens.
4. A broadband imaging lens as described in claim 1, characterized in that, A first SOMA sheet is provided between the third lens and the second aluminum spacer; a second SOMA sheet is provided between the image side of the fourth lens and the lens barrel; a third SOMA sheet is provided between the third aluminum spacer and the sixth lens.
5. A broadband imaging lens as described in claim 1, characterized in that, An aperture stop is provided between the second lens and the third lens, and the aperture stop is located on the object side surface of the third lens.
6. A broadband imaging lens as described in claim 1, characterized in that, The first aluminum press ring, the second aluminum press ring, and the third aluminum press ring are fixed to the inner wall of the lens barrel by gluing.
7. A broadband imaging lens as described in claim 1, characterized in that, A sealing ring is provided between the first lens and the aluminum lens barrel.
8. A broadband imaging lens as described in any one of claims 1-7, characterized in that, The spectral range of the lens is 400~1000nm, the central MTF satisfies 32lp / mm > 0.5, and the edge MTF satisfies 32lp / mm > 0.3.