A large aperture ultraviolet imaging lens

Abstract

This disclosure pertains to the field of lens technology and relates to a large-aperture ultraviolet imaging lens, comprising a first lens to an eighth lens arranged sequentially along the optical axis from the object side to the image side; the first lens is a biconvex lens, the second lens is a negative meniscus lens, the third lens is a biconvex lens, the fourth lens is a biconvex lens, the fifth lens is a negative meniscus lens, the sixth lens is a negative meniscus lens, the seventh lens is a positive meniscus lens, and the eighth lens is a plano-concave lens; the fourth and fifth lenses are cemented together to form a cemented lens; the first, second, and third lenses form the front lens group with a combined focal length of f1; the fourth, fifth, sixth, seventh, and eighth lenses form the rear lens group with a combined focal length of f2; the value of f1 / f2 is between 0.7 and 0.9. The optical structure of this disclosure achieves imaging in the ultraviolet band with an aperture of F2.4, a target surface area of ​​φ30mm, and good resolution consistency across different fields of view, resulting in higher image quality.

Description

Technical Field

[0001] This disclosure belongs to the field of lens technology and relates to a large-aperture ultraviolet imaging lens. Background Technology

[0002] In today's era of rapid technological advancement, optical inspection technology plays a crucial role in numerous fields. Color sorting technology, as an important branch of optical inspection, is continuously expanding its application scope, moving from traditional agricultural product sorting to cutting-edge fields such as industrial inspection and medical diagnosis. Ultraviolet (UV) color sorting lenses, as a key component of color sorting technology, demonstrate significant advantages in complex optical inspection tasks due to their unique performance. Ultraviolet light can penetrate some materials that are opaque under visible light, thus detecting the internal components of the material. This is extremely helpful in identifying the moisture content, impurities, and other characteristics of materials.

[0003] During the color sorting process, ultraviolet lenses can provide more spectral information, enabling the sorting system to more accurately distinguish materials with similar colors but different qualities, thereby improving the accuracy and efficiency of sorting.

[0004] Existing ultraviolet color sorting lenses suffer from low resolution consistency across different fields of view, resulting in image quality that fails to meet high requirements. Utility Model Content

[0005] To overcome the above problems, this disclosure provides a large-aperture ultraviolet imaging lens.

[0006] The technical solution disclosed herein is as follows: A large-aperture ultraviolet imaging lens includes a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the optical axis from the object side to the image side. The first lens is a biconvex lens, the second lens is a negative meniscus lens, the third lens is a biconvex lens, the fourth lens is a biconvex lens, the fifth lens is a negative meniscus lens, the sixth lens is a negative meniscus lens, the seventh lens is a positive meniscus lens, and the eighth lens is a plano-concave lens. The fourth lens and the fifth lens are cemented together to form a cemented lens; The first lens, the second lens, and the third lens constitute the front lens group, with a combined focal length of f1. The fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens form the rear lens group, with a combined focal length of f2; The value of f1 / f2 is between 0.7 and 0.9.

[0007] Furthermore, the air gap between the first lens and the second lens is 4–4.2 mm; The air gap between the second lens and the third lens is 0.1–0.2 mm; The air gap between the third lens and the cemented lens is 10.5–10.8 mm; The air gap between the cemented lens and the sixth lens is 2.8–3 mm; The air gap between the sixth lens and the seventh lens is 0.3–0.4 mm; The air gap between the seventh lens and the eighth lens is 5.8 to 6.2 mm.

[0008] Furthermore, the diameter of the image circle of the lens is Φ, and the focal length of the lens is f; The image circle diameter Φ and the lens focal length f satisfy: 0.55 < Φ / f < 0.65.

[0009] Furthermore, the first lens, the third lens, the fourth lens, and the seventh lens are made of glass, and have the same refractive index and Abbe number; The second, fifth, sixth, and eighth lenses are made of fused silica.

[0010] Furthermore, the first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, and eighth lens are all spherical lenses.

[0011] Public disclosure has the following beneficial effects: The optical structure disclosed herein can image in the ultraviolet band with an aperture of F2.4 and a target surface of φ30mm. It has good resolution consistency across different fields of view and can achieve higher imaging quality.

[0012] All lenses disclosed herein can be spherical mirrors, resulting in low production costs. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the optical structure of an embodiment of this disclosure.

[0014] Figure 2 This is a graph of the modulation transfer function of an embodiment of this disclosure.

[0015] Figure 3 This is a distorted image representing an embodiment of this disclosure.

[0016] The reference numerals in the figure are as follows: L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; G, aperture stop; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; Q, front lens group; H, rear lens group. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0018] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described object changes. To keep the following description of the embodiments of this disclosure clear and concise, detailed descriptions of some known functions and components are omitted.

[0019] The present disclosure will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0020] A large-aperture ultraviolet imaging lens includes a first lens L1, a second lens L2, a third lens L3, an aperture stop G, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, and an eighth lens L8 arranged sequentially along the optical axis from the object side to the image side. The first lens L1 is a biconvex lens, the second lens L2 is a negative meniscus lens, the third lens L3 is a biconvex lens, the fourth lens L4 is a biconvex lens, the fifth lens L5 is a negative meniscus lens, the sixth lens L6 is a negative meniscus lens, the seventh lens L7 is a positive meniscus lens, and the eighth lens L8 is a plano-concave lens. The fourth lens L4 and the fifth lens L5 are cemented together to form a cemented lens; The first lens L1, the second lens L2 and the third lens L3 form the front group lens Q, with a combined focal length of f1. The fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7 and the eighth lens L8 form the rear lens group H, with a combined focal length of f2; The value of f1 / f2 is between 0.7 and 0.9.

[0021] Furthermore, the air gap between the first lens L1 and the second lens L2 is 4 to 4.2 mm; The air gap between the second lens L2 and the third lens L3 is 0.1–0.2 mm; The air gap between the third lens L4 and the cemented lens is 10.5–10.8 mm; The air gap between the cemented lens and the sixth lens L6 is 2.8–3 mm; The air gap between the sixth lens L6 and the seventh lens L7 is 0.3–0.4 mm; The air gap between the seventh lens L7 and the eighth lens L8 is 5.8 to 6.2 mm.

[0022] Furthermore, the diameter of the image circle of the lens is Φ, and the focal length of the lens is f; The image circle diameter Φ and the lens focal length f satisfy: 0.55 < Φ / f < 0.65.

[0023] Furthermore, the first lens L1, the third lens L3, the fourth lens L4, and the seventh lens L7 are made of glass, and have the same refractive index and Abbe number; The second lens L2, the fifth lens L5, the sixth lens L6 and the eighth lens L8 are made of fused silica.

[0024] Furthermore, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 are all spherical lenses.

[0025] In one embodiment of this disclosure, the lens operates in the wavelength range of 360-400 nm. The parameters of each lens are shown in Table 1 below.

[0026] Table 1

[0027] Figure 2 The graph shows the modulation transfer function curves of this embodiment. As can be seen from the graph, the modulation transfer function value per millimeter at the cutoff frequency of 40 line pairs is greater than 0.5 across the entire field of view, and the modulation transfer function curves of each field of view are very concentrated, with good resolution consistency.

[0028] Figure 3The distortion diagram of this embodiment shows that the distortion value does not exceed 0.5% across the entire field of view, thus avoiding image distortion caused by image deformation.

[0029] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0030] The units described in the embodiments of this disclosure can be implemented in software or hardware. The names of the units are not, in some cases, intended to limit the specific unit.

[0031] The functions described above in this document can be performed at least in part by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), and so on.

[0032] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

[0033] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0034] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

[0035] The following points should be noted regarding this disclosure: (1) The accompanying drawings of the embodiments of this disclosure only involve the structures involved in the embodiments of this disclosure. Other structures can be referred to the general design.

[0036] (2) Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0037] The above description is merely an embodiment of this disclosure and does not limit the patent scope of this disclosure. Any equivalent structure made using the content of this disclosure and its drawings, or directly or indirectly applied to other related technical fields, is similarly included within the patent protection scope of this disclosure.

Claims

1. A large aperture ultraviolet imaging lens characterized in that, It includes a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged sequentially along the optical axis from the object side to the image side; The first lens is a biconvex lens, the second lens is a negative meniscus lens, the third lens is a biconvex lens, the fourth lens is a biconvex lens, the fifth lens is a negative meniscus lens, the sixth lens is a negative meniscus lens, the seventh lens is a positive meniscus lens, and the eighth lens is a plano-concave lens. The fourth lens and the fifth lens are cemented together to form a cemented lens; The first lens, the second lens, and the third lens constitute the front lens group, with a combined focal length of f1. The fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens form the rear lens group, with a combined focal length of f2; The value of f1 / f2 is between 0.7 and 0.

9.

2. The large aperture ultraviolet imaging lens of claim 1, wherein, The air gap between the first lens and the second lens is 4 to 4.2 mm; The air gap between the second lens and the third lens is 0.1–0.2 mm; The air gap between the third lens and the cemented lens is 10.5–10.8 mm; The air gap between the cemented lens and the sixth lens is 2.8–3 mm; The air gap between the sixth lens and the seventh lens is 0.3–0.4 mm; The air gap between the seventh lens and the eighth lens is 5.8 to 6.2 mm.

3. The large aperture ultraviolet imaging lens of claim 2, wherein, The lens has an image circle diameter of Φ and a focal length of f. The image circle diameter Φ and the lens focal length f satisfy: 0.55 < Φ / f < 0.

65.

4. The large aperture ultraviolet imaging lens of claim 3, wherein, The first lens, the third lens, the fourth lens, and the seventh lens are made of glass, and have the same refractive index and Abbe number. The second, fifth, sixth, and eighth lenses are made of fused silica.

5. The large aperture ultraviolet imaging lens of claim 3, wherein, The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are all spherical lenses.

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