Visible light lens

Abstract

The invention relates to the technical field of optical lenses, in particular to a visible light lens. The embodiment of the invention provides a visible light lens which sequentially comprises a first positive lens, a second positive lens, a third negative lens, a fourth negative lens, a fifth positive lens, a sixth positive lens, a seventh positive lens and an eighth negative lens in the light incidence direction, the second positive lens and the third negative lens are attached to form a first doublet lens, and the fifth positive lens and the sixth negative lens are attached to form a second doublet lens. The fourth negative lens and the fifth positive lens are attached to form a second doublet lens, the seventh positive lens and the eighth negative lens are attached to form a third doublet lens, and the other lenses are mutually spaced. The embodiment of the invention provides a visible light lens which is large in relative aperture, low in distortion and high in resolution.

Description

Technical Field

[0001] The present invention relates to the technical field of optical lenses, and in particular to a visible light lens. Background Art

[0002] With the development of modern optical imaging technology, the performance requirements for optical lenses are getting higher and higher. Especially in the fields of security monitoring, medical imaging, industrial detection, etc., the demand for large relative aperture, low distortion and high resolution of the lens is particularly urgent. Large relative aperture means that the lens can receive more light, thus providing clear images even in low light conditions. Low distortion ensures the authenticity and accuracy of the image. In addition, high resolution can provide more detailed information, which is crucial for applications such as image analysis and recognition.

[0003] However, traditional optical lenses often have difficulty meeting these requirements at the same time. For example, although some lenses have large relative apertures, they have large distortion, which affects image quality; while some low-distortion lenses have small relative apertures and limited light receiving capabilities. In addition, as lenses develop towards large relative apertures and low distortion, the optical design and manufacturing difficulty of lenses also increases, requiring the use of more advanced optical design technologies and manufacturing processes. Summary of the invention

[0004] The embodiment of the present invention provides a visible light lens, which can provide a lens with large relative aperture, low distortion and high resolution.

[0005] An embodiment of the present invention provides a visible light lens, which includes a first positive lens, a second positive lens, a third negative lens, a fourth negative lens, a fifth positive lens, a sixth positive lens, a seventh positive lens and an eighth negative lens in sequence along the incident direction of light, wherein the second positive lens and the third negative lens are attached to form a first double-cemented lens, the fourth negative lens and the fifth positive lens are attached to form a second double-cemented lens, the seventh positive lens and the eighth negative lens are attached to form a third double-cemented lens, and the remaining lenses are spaced apart from each other.

[0006] In one possible design, all lenses are standard spherical structures.

[0007] In one possible design, the lens system has a total length of 100mm and an F number of 1.25.

[0008] In one possible design, by optimizing using a merit function, the MTF of the optical system is greater than 0.4 at 166 lp / mm.

[0009] In one possible design, the material of the first positive lens is H-ZLAF73; the material of the second positive lens is H-ZPK7; the material of the third negative lens is ZF8; the material of the fourth negative lens is ZF8; the material of the fifth positive lens is H-ZPK7; the material of the sixth positive lens is H-ZLAF73; the material of the seventh positive lens is H-ZPK7; and the material of the eighth negative lens is H-ZLAF73.

[0010] In a possible design, the front and back curvatures of the first positive lens are 53.231 and 179.234 respectively; the front and back curvatures of the second positive lens are 25.701 and 80.159 respectively; the front and back curvatures of the third negative lens are 80.159 and 15.828 respectively; the front and back curvatures of the fourth negative lens are -21.161 and 39.063 respectively; the front and back curvatures of the fifth positive lens are 39.063 and -25.632 respectively; the front and back curvatures of the sixth positive lens are 105.188 and -49.789 respectively; the front and back curvatures of the seventh positive lens are 19.741 and -2725.867; 58; the front and back curvatures of the eighth negative lens are -2725.867 and 23.758 respectively.

[0011] In one possible design, the center thickness of the first positive lens is 5.947mm; the center thickness of the second positive lens is 9mm; the center thickness of the third negative lens is 4.359mm; the center thickness of the fourth negative lens is 4.426mm; the center thickness of the fifth positive lens is 7.5mm; the center thickness of the sixth positive lens is 6.603mm; the center thickness of the seventh positive lens is 6.656mm; and the center thickness of the eighth negative lens is 4.517mm.

[0012] In a possible design, the center distance between the first positive lens and the second positive lens is 4.439 mm; the center distance between the third negative lens and the fourth negative lens is 17.769 mm; the center distance between the fifth positive lens and the sixth positive lens is 12.549 mm; the center distance between the sixth positive lens and the seventh positive lens is 1 mm; and the center distance between the eighth negative lens and the image plane is 15 mm.

[0013] Compared with the prior art, the present invention has at least the following beneficial effects:

[0014] The present invention provides a large relative aperture, low distortion, high resolution visible light lens, including 8 lenses, three double cemented lens groups, and uses an optimized double Gaussian structure and high refractive index materials to effectively reduce the aberration of the optical system. Under the conditions of F number of 1.25, aperture of 48mm, and focal length of 50mm, the present invention achieves a full field distortion of less than 0.5%, a total system length of 100mm, and can match 3μm detector pixels. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention 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 some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 is a schematic structural diagram of a visible light lens provided by an embodiment of the present invention;

[0017] Figure 2 An embodiment of the present invention provides a distortion curve diagram;

[0018] Figure 3 It is a spatial frequency-OTF coefficient curve diagram provided by an embodiment of the present invention.

[0019] In the figure:

[0020] 1. First positive lens; 2. Second positive lens; 3. Third negative lens; 4. Fourth negative lens; 5. Fifth positive lens; 6. Sixth positive lens; 7. Seventh positive lens; 8. Eighth negative lens; 9. Image plane. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0022] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance; unless otherwise specified or explained, the term "multiple" refers to two or more; the terms "connected" and "fixed" should be understood in a broad sense, for example, "connected" can be a fixed connection, a detachable connection, an integral connection, or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0023] In the description of this specification, it should be understood that the directional words such as "upper" and "lower" described in the embodiments of the present invention are described at the angles shown in the drawings and should not be understood as limiting the embodiments of the present invention. In addition, in the context, it should also be understood that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element.

[0024] like Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a visible light lens, which includes a first positive lens 1, a second positive lens 2, a third negative lens 3, a fourth negative lens 4, a fifth positive lens 5, a sixth positive lens 6, a seventh positive lens 7 and an eighth negative lens 8 in sequence along the incident direction of light, wherein the second positive lens 2 and the third negative lens 3 are attached to form a first double-cemented lens, the fourth negative lens 4 and the fifth positive lens 5 are attached to form a second double-cemented lens, the seventh positive lens 7 and the eighth negative lens 8 are attached to form a third double-cemented lens, and the remaining lenses are spaced apart from each other.

[0025] The present invention provides a large relative aperture, low distortion, high resolution visible light lens, including 8 lenses, three double cemented lens groups, and uses an optimized double Gaussian structure and high refractive index materials to effectively reduce the aberration of the optical system. Under the conditions of F number of 1.25, aperture of 48mm, and focal length of 50mm, the present invention achieves a full field distortion of less than 0.5%, a total system length of 100mm, and can match 3μm detector pixels.

[0026] In some embodiments of the present invention, all lenses are of standard spherical structure.

[0027] In some embodiments of the present invention, the total length of the lens system is 100 mm, the F number is 1.25, it can support a detector with a pixel size of 3 μm, the maximum distortion is less than 0.5%, and it has a high imaging quality.

[0028] In some embodiments of the present invention, by using the merit function for optimization, the MTF of the optical system at 166 lp / mm is greater than 0.4.

[0029] like Figure 3 As shown, the present invention is optimized by using the evaluation function, and the MTF of the optical system at 166lp / mm is greater than 0.4.

[0030] In some embodiments of the present invention, the material of the first positive lens 1 is H-ZLAF73; the material of the second positive lens 2 is H-ZPK7; the material of the third negative lens 3 is ZF8; the material of the fourth negative lens 4 is ZF8; the material of the fifth positive lens 5 is H-ZPK7; the material of the sixth positive lens 6 is H-ZLAF73; the material of the seventh positive lens 7 is H-ZPK7; and the material of the eighth negative lens 8 is H-ZLAF73.

[0031] The present invention adopts double-cemented lenses and high-refractive index materials to effectively reduce the chromatic aberration of the optical system. By continuously optimizing the hammer shape of the optical system, the system only uses three lens materials, which greatly reduces the complexity of the lens processing process and reduces the cost.

[0032] In some embodiments of the present invention, the front and back curvatures of the first positive lens 1 correspond to 53.231 and 179.234 respectively; the front and back curvatures of the second positive lens 2 correspond to 25.701 and 80.159 respectively; the front and back curvatures of the third negative lens 3 correspond to 80.159 and 15.828 respectively; the front and back curvatures of the fourth negative lens 4 correspond to -21.161 and 39.063 respectively; the front and back curvatures of the fifth positive lens 5 correspond to 39.063 and -25.632 respectively; the front and back curvatures of the sixth positive lens 6 correspond to 105.188 and -49.789 respectively; the front and back curvatures of the seventh positive lens 7 correspond to 19.741 and -2725.867; 58; the front and back curvatures of the eighth negative lens 8 correspond to -2725.867 and 23.758 respectively.

[0033] In some embodiments of the present invention, the center thickness of the first positive lens 1 is 5.947 mm; the center thickness of the second positive lens 2 is 9 mm; the center thickness of the third negative lens 3 is 4.359 mm; the center thickness of the fourth negative lens 4 is 4.426 mm; the center thickness of the fifth positive lens 5 is 7.5 mm; the center thickness of the sixth positive lens 6 is 6.603 mm; the center thickness of the seventh positive lens 7 is 6.656 mm; and the center thickness of the eighth negative lens 8 is 4.517 mm.

[0034] In some embodiments of the present invention, the center distance between the first positive lens 1 and the second positive lens 2 is 4.439 mm; the center distance between the third negative lens 3 and the fourth negative lens 4 is 17.769 mm; the center distance between the fifth positive lens 5 and the sixth positive lens 6 is 12.549 mm; the center distance between the sixth positive lens 6 and the seventh positive lens 7 is 1 mm; the center distance between the eighth negative lens 8 and the image plane 9 is 15 mm.

[0035] In summary, the parameters of each lens in the visible light lens can be shown in the following table:

[0036]

[0037] The lens of the present invention has an operating spectrum of 486-656nm, a system focal length of 50mm, a full field of view of 7.6°, and effectively reduces system aberrations by optimizing the curvature radius, thickness, and air spacing of eight groups of lenses.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A visible light lens, characterized in that: The invention comprises a first positive lens, a second positive lens, a third negative lens, a fourth negative lens, a fifth positive lens, a sixth positive lens, a seventh positive lens and an eighth negative lens in sequence along the incident direction of light, wherein the second positive lens and the third negative lens are attached to form a first double-cemented lens, the fourth negative lens and the fifth positive lens are attached to form a second double-cemented lens, the seventh positive lens and the eighth negative lens are attached to form a third double-cemented lens, and the remaining lenses are spaced apart from each other.

2. The visible light lens according to claim 1, characterized in that: All lenses are standard spherical structures.

3. The visible light lens according to claim 1, wherein: The total length of the lens system is 100mm and the F number is 1.

25.

4. The visible light lens according to claim 1, wherein: By using the evaluation function for optimization, the MTF of the optical system is greater than 0.4 at 166lp / mm.

5. The visible light lens according to claim 1, characterized in that: The material of the first positive lens is H-ZLAF73; the material of the second positive lens is H-ZPK7; the material of the third negative lens is ZF8; the material of the fourth negative lens is ZF8; the material of the fifth positive lens is H-ZPK7; the material of the sixth positive lens is H-ZLAF73; the material of the seventh positive lens is H-ZPK7; the material of the eighth negative lens is H-ZLAF73.

6. The visible light lens according to claim 1, wherein: The front and back curvatures of the first positive lens are 53.231 and 179.234 respectively; the front and back curvatures of the second positive lens are 25.701 and 80.159 respectively; the front and back curvatures of the third negative lens are 80.159 and 15.828 respectively; the front and back curvatures of the fourth negative lens are -21.161 and 39.063 respectively; the front and back curvatures of the fifth positive lens are 39.063 and -25.632 respectively; the front and back curvatures of the sixth positive lens are 105.188 and -49.789 respectively; the front and back curvatures of the seventh positive lens are 19.741 and -2725.867; 58; the front and back curvatures of the eighth negative lens are -2725.867 and 23.758 respectively.

7. The visible light lens according to claim 1, wherein: The center thickness of the first positive lens is 5.947mm; the center thickness of the second positive lens is 9mm; the center thickness of the third negative lens is 4.359mm; the center thickness of the fourth negative lens is 4.426mm; the center thickness of the fifth positive lens is 7.5mm; the center thickness of the sixth positive lens is 6.603mm; the center thickness of the seventh positive lens is 6.656mm; and the center thickness of the eighth negative lens is 4.517mm.

8. The visible light lens according to claim 1, wherein: The center distance between the first positive lens and the second positive lens is 4.439 mm; the center distance between the third negative lens and the fourth negative lens is 17.769 mm; the center distance between the fifth positive lens and the sixth positive lens is 12.549 mm; the center distance between the sixth positive lens and the seventh positive lens is 1 mm; the center distance between the eighth negative lens and the image plane is 15 mm.

Images