Visible light ultra-large field-of-view optical structure

Abstract

The invention belongs to the technical field of optical engineering, and particularly relates to a visible light ultra-large field-of-view optical structure which sequentially comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power, a fourth lens with positive focal power, a diaphragm and a fifth lens with positive focal power from an object side to an image side. The focal power of the sixth lens is positive; the focal power of the seventh lens is negative; all the lenses are spherical lenses, the centers of spheres on the two sides coincide with the optical axis of the system, five lens materials are adopted, the installation and adjustment tolerance between the lenses is loose, optical materials are easy to prepare, the excellent imaging quality is achieved, the 150-degree optical field of view and three-order aberration correction of a visible spectrum section can be achieved, the preparation process of the optical system is simplified, and the cost is reduced. In addition, the optical structure has the advantages of being compact in structure, easy to integrate, excellent in image quality and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical engineering, and particularly relates to a visible light ultra-large field of view optical structure. Background Art

[0002] As an important tool for astronomical research, the telescope can not only deeply explore the mysteries of the universe, but also has a wide range of application fields. Among them, the telescope has unique advantages and potential in environmental monitoring, including agricultural production, photovoltaic industry, aerospace, astronomical observation, etc. Through the observation, remote sensing and data analysis of the telescope, the changes in the environment can be understood, and sustainable development and ecological protection can be promoted.

[0003] To further improve the environmental monitoring technology, for fields such as agricultural production, photovoltaic industry, aerospace, and astronomical observation, the research and development of high-quality sky imaging devices have important application value and broad application prospects. Currently, in order to meet the requirement of system miniaturization for the developed visible light ultra-large field of view optical system, when the optical field of view exceeds 140°, a high-order aspherical lens is added to the optical system to balance the aberration. Although the application of the aspherical lens can effectively optimize the imaging quality of the optical system and increase the design freedom, the processing and alignment tolerances of its aspherical lens are relatively strict, and the detection difficulty is relatively high, which not only increases the manufacturing difficulty of the optical system, but also increases the manufacturing cost and time cost. Summary of the Invention

[0004] In view of this, the present invention aims to provide a visible light ultra-large field of view optical structure to solve the problems of strict alignment tolerances, high detection difficulty, increased manufacturing cost and time cost caused by using aspherical lenses when the optical field of view exceeds 140°.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: A visible light ultra-large field of view optical structure, which sequentially includes a first lens with a negative optical power, a second lens with a negative optical power, a third lens with a positive optical power, a fourth lens with a positive optical power, a diaphragm, a fifth lens with a positive optical power, a sixth lens with a positive optical power, a seventh lens with a negative optical power, and an image plane from the object side to the image side; the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all spherical lenses, and the centers of both sides of each lens coincide with the optical axis of the visible light ultra-large field of view optical structure; The first lens and the second lens are made of a first optical material, the third lens and the seventh lens are made of a second optical material, the fourth lens is made of a third optical material, the fifth lens is made of a fourth optical material, and the sixth lens is made of a fifth optical material; The refractive index ranges and Abbe number ranges of the first optical material, the second optical material, the third optical material, the fourth optical material, and the fifth optical material are all different.

[0006] Further, the refractive index Nd of the first optical material satisfies: 1.8 ≤ Nd ≤ 1.82, and the Abbe number Vd of the first optical material satisfies: 46 ≤ Vd ≤ 48.

[0007] Further, the refractive index Nd of the second optical material satisfies: 1.90 ≤ Nd ≤ 1.92, and the Abbe number Vd of the second optical material satisfies: 18.5 ≤ Vd ≤ 19.

[0008] Further, the refractive index Nd of the third optical material satisfies: 1.49 ≤ Nd ≤ 1.52, and the Abbe number Vd of the third optical material satisfies: 80 ≤ Vd ≤ 82.

[0009] Further, the refractive index Nd of the fourth optical material satisfies: 1.64 ≤ Nd ≤ 1.68, and the Abbe number Vd of the fourth optical material satisfies: 58 ≤ Vd ≤ 59.

[0010] Further, the refractive index Nd of the fifth optical material satisfies: 1.57 ≤ Nd ≤ 1.59, and the Abbe number Vd of the fifth optical material satisfies: 61 ≤ Vd ≤ 62.

[0011] Further, the object side surface of the first lens is convex, and the image side surface of the first lens is concave; The object side surface of the second lens is flat, and the image side surface of the second lens is concave; The object side surface of the third lens is convex, and the image side surface of the third lens is convex; The object side surface of the fourth lens is convex, and the image side surface of the fourth lens is convex; The object side surface of the fifth lens is convex, and the image side surface of the fifth lens is convex; The object side surface of the sixth lens is convex, and the image side surface of the sixth lens is convex; The object side surface of the seventh lens is concave, and the image side surface of the seventh lens is concave.

[0012] Further, the focal length range of the first lens is: -20 mm to -25 mm; the focal length range of the second lens is: -4 mm to -5 mm; the focal length range of the third lens is: 14 mm to 15 mm; the focal length range of the fourth lens is: 17 mm to 18 mm; the focal length range of the fifth lens is 10 mm to 11 mm; the focal length range of the sixth lens is 4 mm to 5 mm; the focal length range of the seventh lens is -6 mm to -7 mm.

[0013] Further, the thickness of the first lens is 0.8 mm to 1 mm, and the distance between the first lens and the second lens is 7 mm to 7.5 mm; The thickness of the second lens is 0.8 mm to 1 mm, and the distance between the second lens and the third lens is 2.6 mm to 2.7 mm; The thickness of the third lens is 3 mm to 3.5 mm, and the distance between the third lens and the fourth lens is 5 mm to 6 mm; The thickness of the fourth lens is 0.8 mm to 1 mm, and the distance between the fourth lens and the fifth lens is 1.8 mm to 2 mm; The thickness of the fifth lens is 0.8 mm to 1 mm, and the distance between the fifth lens and the sixth lens is 0.1 mm to 0.3 mm; The thickness of the sixth lens is 1.3 mm to 1.5 mm, and the distance between the sixth lens and the seventh lens is 0.1 mm to 0.3 mm; The thickness of the seventh lens is 1.5 mm to 1.7 mm, and the distance between the seventh lens and the image plane is 3 mm to 3.3 mm.

[0014] Further, the aperture number F of the visible light ultra-wide field optical structure is 1.6 to 1.9, and the working band is 480 nm to 670 nm.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: The visible light ultra-wide field optical structure of the present invention adopts a global spherical lens combination method for optical structure design. Five types of lens materials are used, with a total of seven spherical lenses. The assembly and adjustment tolerances between the lenses are relatively loose, the optical material preparation is simple, and excellent imaging quality is achieved. An optical field of 150° can be realized, and third-order aberration correction in the visible spectral band is achieved. This not only simplifies the preparation process of the optical system but also reduces the production cost. In addition, the optical structure of the present invention also has the characteristics of compact structure, simple integration, and excellent image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 is a schematic diagram of a visible light ultra-wide field optical structure according to an embodiment of the present invention; Figure 2 is a light path diagram of a visible light ultra-wide field optical structure according to an embodiment of the present invention; Figure 3 Spot diagrams of each field of view of a visible light ultra-wide field of view optical structure according to an embodiment of the present invention

[0017] Description of reference numerals: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Diaphragm; 6. Fifth lens; 7. Sixth lens; 8. Seventh lens; 9. Image plane. Detailed implementation manners

[0018] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. Similar elements in different embodiments are labeled with related similar reference numerals. In the following embodiments, many detailed descriptions are provided to enable a better understanding of the present invention. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present invention are not shown or described in the specification, in order to avoid the core part of the present invention being overwhelmed by excessive descriptions. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the descriptions in the specification and the general technical knowledge in the art.

[0019] It should be noted that, without conflict, the embodiments and features in the embodiments of the present invention can be combined with each other to form various implementation manners. At the same time, the steps or actions in the method descriptions can also be adjusted in the order that can be obviously understood by those skilled in the art. Therefore, the various sequences in the specification and drawings are only for clearly describing a certain embodiment, and do not mean that they are the necessary sequences, unless it is stated that a certain sequence must be followed.

[0020] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise stated, the meaning of "a plurality" is two or more.

[0021] In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

[0022] The present invention will be described in detail below with reference to the drawings and in conjunction with embodiments.

[0023] As Figures 1 to 3 shown, a visible light ultra-large field of view optical structure successively includes a first lens 1 with a negative optical power, a second lens 2 with a negative optical power, a third lens 3 with a positive optical power, a fourth lens 4 with a positive optical power, a fifth lens 6 with a positive optical power, a sixth lens 7 with a positive optical power, a seventh lens 8 with a negative optical power, and an image plane 9 from the object side to the image side. The aperture stop 5 is located between the fourth lens 4 and the fifth lens 6, and the aperture range of the aperture stop 5 is 3 mm to 4 mm.

[0024] Specifically, the visible light ultra-large field of view optical structure uses 7 spherical lenses to balance the aberration of the light beam from an infinitely distant target. For points on the optical axis of the optical structure, the aberration is small, but for points off the optical axis, especially at the edge of the field of view, a relatively large aberration is generated, which is corrected by the 7 spherical lenses. The light rays from an infinitely distant target reach the image plane after passing through the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 6, the sixth lens 7, and the seventh lens 8. Among them, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 6, the sixth lens 7, and the seventh lens 8 are lenses with optical power, and the connecting lines of the centers of all the lenses coincide with the optical axis of the visible light ultra-large field of view optical structure.

[0025] Specifically, the aperture number F of the visible light ultra-large field of view optical structure is 1.6 to 1.9, and the working wavelength range is 480 nm to 670 nm.

[0026] Specifically, the lens materials are five different grades of optical materials. Among them, the first lens 1 and the second lens 2 are made of the first optical material, the third lens 3 and the seventh lens 8 are made of the second optical material, the fourth lens 4 is made of the third optical material, the fifth lens 6 is made of the fourth optical material, and the sixth lens 7 is made of the fifth optical material; The refractive index ranges and Abbe number ranges of the first optical material, the second optical material, the third optical material, the fourth optical material, and the fifth optical material are all different.

[0027] Specifically, imaging is corrected by optical materials with five different refractive indices and Abbe numbers of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 6, the sixth lens 7, and the seventh lens 8, so as to obtain a large field of view and high-quality imaging. The refractive index Nd of the first optical material satisfies: 1.8 ≤ Nd ≤ 1.82, and the Abbe number Vd of the first optical material satisfies: 46 ≤ Vd ≤ 48; the refractive index Nd of the second optical material and the sixth optical material satisfies: 1.90 ≤ Nd ≤ 1.92, and the Abbe number Vd of the second optical material and the sixth optical material satisfies: 18.5 ≤ Vd ≤ 19; the refractive index Nd of the third optical material satisfies: 1.49 ≤ Nd ≤ 1.52, and the Abbe number Vd of the third optical material satisfies: 80 ≤ Vd ≤ 82; the refractive index Nd of the fourth optical material satisfies: 1.64 ≤ Nd ≤ 1.68, and the Abbe number Vd of the fourth optical material satisfies: 58 ≤ Vd ≤ 59; the refractive index Nd of the fifth optical material satisfies: 1.57 ≤ Nd ≤ 1.59, and the Abbe number Vd of the fifth optical material satisfies: 61 ≤ Vd ≤ 62.

[0028] It should be noted that the present application does not specifically limit the compositions of the first optical material, the second optical material, the third optical material, the fourth optical material, and the fifth optical material. It is only required that the five materials respectively meet the corresponding refractive index ranges and Abbe number ranges.

[0029] Specifically, the object side surface of the first lens 1 is convex outward, and the image side surface of the first lens 1 is concave inward; the object side surface of the second lens 2 is flat, and the image side surface of the second lens 2 is concave inward; the object side surface of the third lens 3 is convex outward, and the image side surface of the third lens 3 is convex outward; the object side surface of the fourth lens 4 is convex outward, and the image side surface of the fourth lens 4 is convex outward; the object side surface of the fifth lens 6 is convex outward, and the image side surface of the fifth lens 6 is convex outward; the object side surface of the sixth lens 7 is convex outward, and the image side surface of the sixth lens 7 is convex outward; the object side surface of the seventh lens 8 is concave inward, and the image side surface of the seventh lens 8 is concave inward.

[0030] Specifically, through the optimized design of different optical material combinations, the curvature radii of the two sides of the lenses, and the lens thicknesses, the focal lengths of the respective lenses are obtained. The focal length range of the first lens 1 is: -20 mm to -25 mm; the focal length range of the second lens 2 is: -4 mm to -5 mm; the focal length range of the third lens 3 is: 14 mm to 15 mm; the focal length range of the fourth lens 4 is: 17 mm to 18 mm; the focal length range of the fifth lens 6 is 10 mm to 11 mm; the focal length range of the sixth lens 7 is 4 mm to 5 mm; the focal length range of the seventh lens 8 is -6 mm to -7 mm.

[0031] Specifically, the thickness of the first lens 1 is 0.8 mm to 1 mm, and the distance between the first lens 1 and the second lens 2 is 7 mm to 7.5 mm; the thickness of the second lens 2 is 0.8 mm to 1 mm, and the distance between the second lens 2 and the third lens 3 is 2.6 mm to 2.7 mm; the thickness of the third lens 3 is 3 mm to 3.5 mm, and the distance between the third lens 3 and the fourth lens 4 is 5 mm to 6 mm; the thickness of the fourth lens 4 is 0.8 mm to 1 mm, and the distance between the fourth lens 4 and the fifth lens 6 is 1.8 mm to 2 mm; the thickness of the fifth lens 6 is 0.8 mm to 1 mm, and the distance between the fifth lens 6 and the sixth lens 7 is 0.1 mm to 0.3 mm; the thickness of the sixth lens 7 is 1.3 mm to 1.5 mm, and the distance between the sixth lens 7 and the seventh lens 8 is 0.1 mm to 0.3 mm; the thickness of the seventh lens 8 is 1.5 mm to 1.7 mm, and the distance between the seventh lens 8 and the image plane 9 is 3 mm to 3.3 mm.

[0032] Furthermore, taking Table 1 as an example for the specific parameters of each lens, where the unit of the curvature radius is mm; the unit of the lens thickness is mm; and the unit of the interval is mm.

[0033] Table 1

[0034] A visible light ultra-wide field of view optical structure according to the present invention adopts a global spherical lens combination method for the design of the optical structure. Five types of lens materials are used, with a total of seven spherical lenses. The first lens 1 collects the energy of far-field light beams within a 150° field of view, and the subsequent six spherical lenses are reasonably combined for aberration correction. Since the optical structure has a relatively large field of view and a relatively wide working wavelength band, a lens combination made of optical materials with specific refractive indices and dispersion coefficients is used to correct the off-axis aberration and chromatic aberration of the optical structure. The alignment tolerance between lenses is relatively loose, the optical material preparation is simple, and excellent imaging quality is achieved. An optical field of view of 150° can be achieved, and third-order aberration correction in the visible spectral band can be realized. It not only simplifies the preparation process of the optical system, but also reduces the production cost. In addition, the visible light ultra-wide field of view optical structure of the present invention also has the characteristics of compact structure, easy integration, and excellent image quality.

[0035] It should be understood that various forms of the processes shown above can be used, steps can be reordered, added, or deleted. For example, the steps described in the disclosure of the present invention can be executed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present invention can be achieved, and no limitations are imposed herein.

[0036] The above specific embodiments do not constitute a limitation on the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A visible light ultra-large field of view optical structure, characterized by: The visible light ultra-large field of view optical structure includes, from the object side to the image side, a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power, a fourth lens with positive optical power, an aperture, a fifth lens with positive optical power, a sixth lens with positive optical power, a seventh lens with negative optical power, and an image plane; the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all spherical lenses, and the centers of both sides of the spheres coincide with the optical axis of the visible light ultra-large field of view optical structure; The first lens and the second lens are made of a first optical material, the third lens and the seventh lens are made of a second optical material, the fourth lens is made of a third optical material, the fifth lens is made of a fourth optical material, and the sixth lens is made of a fifth optical material; The refractive index ranges and Abbe number ranges of the first optical material, the second optical material, the third optical material, the fourth optical material and the fifth optical material are all different.

2. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The refractive index Nd of the first optical material satisfies: 1.8≤Nd≤1.82, and the Abbe number Vd of the first optical material satisfies: 46≤Vd≤48.

3. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The refractive index Nd of the second optical material satisfies: 1.90≤Nd≤1.92, and the Abbe number Vd of the second optical material satisfies: 18.5≤Vd≤19.

4. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The refractive index Nd of the third optical material satisfies: 1.49≤Nd≤1.52, and the Abbe number Vd of the third optical material satisfies: 80≤Vd≤82.

5. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The refractive index Nd of the fourth optical material satisfies: 1.64≤Nd≤1.68, and the Abbe number Vd of the fourth optical material satisfies: 58≤Vd≤59.

6. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The refractive index Nd of the fifth optical material satisfies: 1.57≤Nd≤1.59, and the Abbe number Vd of the fifth optical material satisfies: 61≤Vd≤62.

7. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The object side surface of the first lens is an outer convex surface, and the image side surface of the first lens is an inner concave surface; The object side surface of the second lens is a flat surface, and the image side surface of the second lens is an inner concave surface; The object side surface of the third lens is an outer convex surface, and the image side surface of the third lens is an outer convex surface; The object side surface of the fourth lens is an outer convex surface, and the image side surface of the fourth lens is an outer convex surface; The object side surface of the fifth lens is an outer convex surface, and the image side surface of the fifth lens is an outer convex surface; The object side surface of the sixth lens is an outer convex surface, and the image side surface of the sixth lens is an outer convex surface; The object side surface of the seventh lens is an inner concave surface, and the image side surface of the seventh lens is an inner concave surface.

8. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The focal length range of the first lens is: -20mm~-25mm; the focal length range of the second lens is: -4mm~-5mm; the focal length range of the third lens is: 14mm~15mm; the focal length range of the fourth lens is: 17mm~18mm; the focal length range of the fifth lens is: 10mm~11mm; the focal length range of the sixth lens is 4mm~5mm; the focal length range of the seventh lens is -6mm~-7mm.

9. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The thickness of the first lens is 0.8 mm to 1 mm, and the distance between the first lens and the second lens is 7 mm to 7.5 mm; The thickness of the second lens is 0.8 mm to 1 mm, and the distance between the second lens and the third lens is 2.6 mm to 2.7 mm; The thickness of the third lens is 3 mm to 3.5 mm, and the distance between the third lens and the fourth lens is 5 mm to 6 mm; The thickness of the fourth lens is 0.8 mm to 1 mm, and the distance between the fourth lens and the fifth lens is 1.8 mm to 2 mm; The thickness of the fifth lens is 0.8 mm to 1 mm, and the distance between the fifth lens and the sixth lens is 0.1 mm to 0.3 mm; The thickness of the sixth lens is 1.3 mm to 1.5 mm, and the distance between the sixth lens and the seventh lens is 0.1 mm to 0.3 mm; The thickness of the seventh lens is 1.5 mm to 1.7 mm, and the distance between the seventh lens and the image plane is 3 mm to 3.3 mm.

10. The visible light ultra-large field of view optical structure according to claim 1, characterized in that: The aperture number F of the visible light ultra-large field of view optical structure is 1.6-1.9, and the working band is 480nm-670nm.

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