Long-wave infrared ultra-large field-of-view optical structure

Abstract

The invention belongs to the technical field of optical detection, and particularly relates to a long-wave infrared ultra-large field-of-view optical structure. The long-wave infrared ultra-large field-of-view optical structure sequentially comprises a first lens with negative focal power, a second lens with positive focal power, a third lens with negative focal power, a fourth lens with positive focal power, a diaphragm, a fifth lens with negative focal power, a sixth lens with positive focal power and a seventh lens with negative focal power from an object side to an image side, the focal power of the eighth lens is positive; the eight lenses are made of a first optical material, a second optical material and a third optical material, and the three optical materials are different. According to the optical structure, optical materials of three different marks are utilized, lens materials with specific refractive index and dispersion coefficient are combined to correct optical axis outer aberration and chromatic aberration, the preparation process of the optical system is simplified, the production cost is reduced, and 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 detection, and particularly relates to a long-wave infrared ultra-large field-of-view optical structure. Background Art

[0002] As an important tool for astronomical research, a 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, promoting sustainable development and ecological protection.

[0003] To further improve environmental monitoring technology, for fields such as agricultural production, photovoltaic industry, aerospace, and astronomical observation, researching and developing high-quality night sky imaging devices has important application value and broad application prospects. Currently, in order to meet the requirement of system miniaturization in the design of the developed long-wave infrared ultra-large field-of-view optical system, generally more than 5 types of infrared materials are required for aberration balance during the long-wave infrared ultra-large field-of-view optical design. And when the optical field of view exceeds 140°, a high-order aspherical lens is added to the optical system for aberration balance. 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 assembly tolerance of the 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 raises the manufacturing cost and time cost. Summary of the Invention

[0004] In view of this, the present invention aims to provide a long-wave infrared ultra-large field-of-view optical structure to solve the technical problems of the large number of types of infrared materials used and the large manufacturing difficulty of the optical system.

[0005] To achieve the above object, the technical solution of the present invention is realized as follows: A long-wave infrared ultra-large field-of-view optical structure includes, in sequence from the object side to the image side, a first lens with a negative optical power, a second lens with a positive optical power, a third lens with a negative optical power, a fourth lens with a positive optical power, a diaphragm, a fifth lens with a negative optical power, a sixth lens with a positive optical power, a seventh lens with a negative optical power, an eighth lens with a positive optical power, and an image plane; The first lens, the fourth lens, the sixth lens, the seventh lens, and the eighth lens are made of a first optical material, the second lens and the fifth lens are made of a second optical material, and the third lens is made of a third optical material; the first optical material, the second optical material, and the third optical material are all different.

[0006] Furthermore, the refractive index range of the first optical material is 5.48 ≤ Nd ≤ 5.52, and the Abbe number range of the first optical material is 862 ≤ Vd ≤ 866.

[0007] Furthermore, the refractive index range of the second optical material is 2.35 ≤ Nd ≤ 2.39, and the Abbe number range of the second optical material is 15 ≤ Nd ≤ 17.

[0008] Furthermore, the refractive index range of the third optical material is 2.60 ≤ Nd ≤ 2.64, and the Abbe number range of the third optical material is 7 ≤ Vd ≤ 9.

[0009] Furthermore, 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 convex, and the image side surface of the second lens is convex; The object side surface of the third lens is convex, and the image side surface of the third lens is concave; 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 concave, 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 concave; The object side surface of the seventh lens is concave, and the image side surface of the seventh lens is convex; The object side surface of the eighth lens is convex, and the image side surface of the eighth lens is concave.

[0010] Furthermore, the focal length range of the first lens is -4 mm to -4.5 mm; the focal length range of the second lens is 18 mm to 19 mm; the focal length range of the third lens is -9 mm to -10 mm; the focal length range of the fourth lens is 7 mm to 8 mm; the focal length range of the fifth lens is -95 mm to -96 mm, the focal length range of the sixth lens is 5.5 mm to 6 mm, the focal length range of the seventh lens is -11 mm to -11.6 mm; the focal length range of the eighth lens is 4.5 mm to 5 mm.

[0011] Furthermore, the thickness range of the first lens is 0.8 mm to 1 mm, and the interval distance range between the first lens and the second lens is 2.1 mm to 2.3 mm; The thickness range of the second lens is 0.8 mm to 1 mm, and the interval distance range between the second lens and the third lens is 0.3 mm to 0.5 mm; The thickness range of the third lens is 0.8 mm to 1 mm, and the distance range between the third lens and the fourth lens is 5 mm to 6 mm; The thickness range of the fourth lens is 1 mm to 1.2 mm, and the distance range between the fourth lens and the fifth lens is 6.5 mm to 6.8 mm; The thickness range of the fifth lens is 3 mm to 3.5 mm, and the distance range between the fifth lens and the sixth lens is 0.1 mm to 0.3 mm; The thickness range of the sixth lens is 0.6 mm to 0.8 mm, and the distance range between the sixth lens and the seventh lens is 0.4 mm to 0.5 mm; The thickness range of the seventh lens is 0.8 mm to 1 mm; the distance range between the seventh lens and the eighth lens is 3 mm to 3.5 mm; The thickness range of the eighth lens is 2 mm to 2.5 mm; the distance range between the eighth lens and the image plane is 1.4 mm to 1.8 mm.

[0012] Further, the aperture range of the aperture stop is 3 mm to 4 mm.

[0013] Further, the f-number F of the long-wave infrared ultra-wide field of view optical structure is 1 to 1.2, and the working wavelength band of the long-wave infrared ultra-wide field of view optical structure is 8000 nm to 14000 nm.

[0014] Further, the maximum field of view range of the long-wave infrared ultra-wide field of view optical structure is at least 150°.

[0015] Compared with the prior art, the present invention can achieve the following beneficial effects: A long-wave infrared ultra-wide field of view optical structure according to the present invention uses 3 types of lens materials and a total of 8 spherical lenses. The first lens collects the energy of far-field light beams within a 150° field of view, and the subsequent 7 spherical lenses are reasonably combined for aberration correction. An optical field of view of 150° can be achieved, and the aberration of the light beams from an infinite target is balanced. The optical structure composed of 8 spherical lenses performs third-order aberration correction in the long-wave infrared spectral band. By using three different grades of optical materials and a lens combination made of lens materials with specific refractive index dispersion coefficients, the aberrations and chromatic aberrations outside the optical axis are corrected, which not only simplifies the preparation process of the optical system but also reduces the production cost. The optical structure of the present invention also has the characteristics of compact structure, simple integration, and excellent image quality. Description of the Drawings

[0016] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings: Figure 1 It is a schematic diagram of a long-wave infrared ultra-large field-of-view optical structure according to an embodiment of the present invention; Figure 2 It is a light path diagram of a long-wave infrared ultra-large field-of-view optical structure according to an embodiment of the present invention; Figure 3 It is a modulation transfer function diagram of a long-wave infrared ultra-large field-of-view optical structure according to an embodiment of the present invention; Figure 4 It is a spot diagram of each field of view of a long-wave infrared ultra-large 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. Aperture; 6. Fifth lens; 7. Sixth lens; 8. Seventh lens; 9. Eighth lens; 10. Image plane. Detailed implementation manners

[0018] In order to make the purpose, technical solutions and advantages of the present invention clearer, the following further details the present invention in combination with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation to the present invention. Similar elements in different embodiments are labeled with related similar reference numerals. In the following embodiments, many details are described to make the present invention better understood. 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, which is to avoid the core part of the present invention being overwhelmed by excessive description. 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 according to the description in the specification and the general technical knowledge in the field.

[0019] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other to form various embodiments. At the same time, the steps or actions in the method description can also be adjusted in the order that can be obviously seen by those skilled in the art. Therefore, the various orders in the specification and drawings are only for clearly describing a certain embodiment and do not mean that they are the necessary order, unless it is stated that a certain order 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, and 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 therefore should not be construed as a limitation to 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 specified, the meaning of "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 4 shown, a long-wave infrared ultra-large field-of-view optical structure includes, in sequence from the object side to the image side, a first lens 1 with a negative optical power, a second lens 2 with a positive optical power, a third lens 3 with a negative optical power, a fourth lens 4 with a positive optical power, a stop 5, a fifth lens 6 with a negative optical power, a sixth lens 7 with a positive optical power, a seventh lens 8 with a negative optical power, an eighth lens 9 with a positive optical power, and an image plane 10. The stop 5 is located between the fourth lens 4 and the fifth lens 6, and the aperture range of the stop 5 is 3 mm to 4 mm. The f-number F of the long-wave infrared ultra-large field-of-view optical structure is 1 to 1.2, the working wavelength band of the long-wave infrared ultra-large field-of-view optical structure is 8000 nm to 14000 nm, and the maximum field-of-view range is at least 150°.

[0024] Specifically, the lens is made of three different grades of optical materials. Among them, the first lens 1, the fourth lens 4, the sixth lens 7, the seventh lens 8, and the eighth lens 9 are made of the first optical material, the second lens 2 and the fifth lens 6 are made of the second optical material, and the third lens 3 is made of the third optical material; the first optical material, the second optical material, and the third optical material are all different.

[0025] Further, germanium is used for the first optical material; zinc sulfide is used for the second optical material; zinc selenide is used for the third optical material.

[0026] The refractive index range of the first optical material is 5.48 ≤ Nd ≤ 5.52, and the Abbe number range of the first optical material is 862 ≤ Vd ≤ 866; the refractive index range of the second optical material is 2.35 ≤ Nd ≤ 2.39, and the Abbe number range of the second optical material is 15 ≤ Nd ≤ 17; the refractive index range of the third optical material is 2.60 ≤ Nd ≤ 2.64, and the Abbe number range of the third optical material is 7 ≤ Vd ≤ 9.

[0027] The beam is corrected by the three different refractive index and Abbe number optical materials 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, the seventh lens 8, and the eighth lens 9, so as to obtain a large field of view and high-quality imaging.

[0028] Specifically, the object side of the first lens 1 is a convex surface, and the image side of the first lens 1 is a concave surface; the object side of the second lens 2 is a convex surface, and the image side of the second lens 2 is a convex surface; the object side of the third lens 3 is a convex surface, and the image side of the third lens 3 is a concave surface; the object side of the fourth lens 4 is a convex surface, and the image side of the fourth lens 4 is a convex surface; the object side of the fifth lens 6 is a concave surface, and the image side of the fifth lens 6 is a convex surface; the object side of the sixth lens 7 is a convex surface, and the image side of the sixth lens 7 is a concave surface; the object side of the seventh lens 8 is a concave surface, and the image side of the seventh lens 8 is a convex surface; the object side of the eighth lens 9 is a convex surface, and the image side of the eighth lens 9 is a concave surface.

[0029] Specifically, through the combination of different optical materials, the optimization design of the double-sided curvature radius and thickness of the lens, the focal lengths of each lens are obtained. The focal length range of the first lens 1 is -4 mm to -4.5 mm; the focal length range of the second lens 2 is 18 mm to 19 mm; the focal length range of the third lens 3 is -9 mm to -10 mm; the focal length range of the fourth lens 4 is 7 mm to 8 mm; the focal length range of the fifth lens 6 is -95 mm to -96 mm; the focal length range of the sixth lens 7 is 5.5 mm to 6 mm; the focal length range of the seventh lens 8 is -11 mm to -11.6 mm; the focal length range of the eighth lens 9 is 4.5 mm to 5 mm.

[0030] Specifically, the thickness range of the first lens 1 is 0.8 mm to 1 mm, and the spacing distance between the first lens 1 and the second lens 2 ranges from 2.1 mm to 2.3 mm; the thickness range of the second lens 2 is 0.8 mm to 1 mm, and the spacing distance between the second lens 2 and the third lens 3 ranges from 0.3 mm to 0.5 mm; the thickness range of the third lens 3 is 0.8 mm to 1 mm, and the spacing distance between the third lens 3 and the fourth lens 4 ranges from 5 mm to 6 mm; the thickness range of the fourth lens 4 is 1 mm to 1.2 mm, and the spacing distance between the fourth lens 4 and the fifth lens 6 ranges from 6.5 mm to 6.8 mm; the thickness range of the fifth lens 6 is 3 mm to 3.5 mm, and the distance between the fifth lens 6 and the sixth lens 7 ranges from 0.1 mm to 0.3 mm; the thickness range of the sixth lens 7 is 0.6 mm to 0.8 mm, and the distance between the sixth lens 7 and the seventh lens 8 ranges from 0.4 mm to 0.5 mm; the thickness range of the seventh lens 8 is 0.8 mm to 1 mm, and the distance between the seventh lens 8 and the eighth lens 9 ranges from 3 mm to 3.5 mm; the thickness range of the eighth lens 9 is 2 mm to 2.5 mm, and the distance between the eighth lens 9 and the image plane 10 ranges from 1.4 mm to 1.8 mm.

[0031] Furthermore, taking the specific parameters of each lens in Table 1 as an example, where the unit of the radius of curvature is mm; the unit of the lens thickness is mm; the unit of the spacing is mm.

[0032] Table 1

[0033] For a long-wave infrared ultra-wide field of view optical structure described in the present invention, 3 types of lens materials are used, with a total of 8 spherical lenses. The first lens collects the energy of the far-field beam within a 150° field of view, and the subsequent 7 spherical lenses are reasonably combined for aberration correction. An optical field of view of 150° can be achieved, and the aberration of the beam for an infinitely distant target is balanced. The optical structure composed of 8 spherical lenses performs third-order aberration correction in the long-wave infrared spectral band. A lens combination made of three different grades of optical materials with specific refractive indices and dispersion coefficients is used to correct off-axis aberrations and chromatic aberrations, which not only simplifies the preparation process of the optical system but also reduces the production cost. The optical structure of the present invention also has the characteristics of compact structure, simple integration, and excellent image quality.

[0034] It should be understood that various forms of the processes shown above can be used, reordering, adding, or deleting steps. 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.

[0035] 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 principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A long-wave infrared ultra-large field of view optical structure, characterized in that: The long-wave infrared ultra-large field of view optical structure includes, from the object side to the image side, a first lens with negative focal power, a second lens with positive focal power, a third lens with negative focal power, a fourth lens with positive focal power, an aperture, a fifth lens with negative focal power, a sixth lens with positive focal power, a seventh lens with negative focal power, an eighth lens with positive focal power, and an image plane; The first lens, the fourth lens, the sixth lens, the seventh lens and the eighth lens are made of a first optical material, the second lens and the fifth lens are made of a second optical material, and the third lens is made of a third optical material; the first optical material, the second optical material and the third optical material are all different.

2. A long-wave infrared ultra-large field of view optical structure according to claim 1, characterized in that: The refractive index range of the first optical material is 5.48≤Nd≤5.52, and the Abbe number range of the first optical material is 862≤Vd≤866.

3. The long-wave infrared ultra-large field of view optical structure according to claim 1, characterized in that: The refractive index range of the second optical material is 2.35≤Nd≤2.39, and the Abbe number range of the second optical material is 15≤Nd≤17.

4. The long-wave infrared ultra-large field of view optical structure according to claim 1, characterized in that: The refractive index range of the third optical material is 2.60≤Nd≤2.64, and the Abbe number range of the third optical material is 7≤Vd≤9.

5. The long-wave infrared 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 an outer convex surface, and the image side surface of the second lens is an outer convex 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 inner concave 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 inner concave 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 inner concave 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 outer convex surface; The object side surface of the eighth lens is an outer convex surface, and the image side surface of the eighth lens is an inner concave surface.

6. The long-wave infrared ultra-large field of view optical structure according to claim 1, characterized in that: The focal length range of the first lens is -4mm~-4.5mm; the focal length range of the second lens is 18mm~19mm; the focal length range of the third lens is -9mm~-10mm; the focal length range of the fourth lens is 7mm~8mm; the focal length range of the fifth lens is -95mm~-96mm, the focal length range of the sixth lens is 5.5mm~6mm, the focal length range of the seventh lens is -11mm~-11.6mm; the focal length range of the eighth lens is 4.5mm~5mm.

7. The long-wave infrared ultra-large field of view optical structure according to claim 1, characterized in that: The thickness of the first lens is in the range of 0.8 mm to 1 mm, and the distance between the first lens and the second lens is in the range of 2.1 mm to 2.3 mm; The thickness of the second lens is in the range of 0.8 mm to 1 mm, and the distance between the second lens and the third lens is in the range of 0.3 mm to 0.5 mm; The thickness of the third lens is in the range of 0.8 mm to 1 mm, and the distance between the third lens and the fourth lens is in the range of 5 mm to 6 mm; The thickness of the fourth lens is in the range of 1 mm to 1.2 mm, and the distance between the fourth lens and the fifth lens is in the range of 6.5 mm to 6.8 mm; The thickness of the fifth lens is in the range of 3 mm to 3.5 mm, and the distance between the fifth lens and the sixth lens is in the range of 0.1 mm to 0.3 mm; The thickness of the sixth lens is in the range of 0.6 mm to 0.8 mm, and the distance between the sixth lens and the seventh lens is in the range of 0.4 mm to 0.5 mm; The thickness of the seventh lens is in the range of 0.8 mm to 1 mm; the distance between the seventh lens and the eighth lens is in the range of 3 mm to 3.5 mm; The thickness of the eighth lens is in the range of 2 mm to 2.5 mm; the distance between the eighth lens and the image plane is in the range of 1.4 mm to 1.8 mm.

8. The long-wave infrared ultra-large field of view optical structure according to claim 1, characterized in that: The aperture range of the aperture is 3mm~4mm.

9. The long-wave infrared ultra-large field of view optical structure according to claim 1, characterized in that: The aperture number F of the long-wave infrared ultra-large field of view optical structure is 1-1.2, and the working band of the long-wave infrared ultra-large field of view optical structure is 8000nm-14000nm.

10. The long-wave infrared ultra-large field of view optical structure according to claim 1, characterized in that: The maximum field of view of the long-wave infrared ultra-large field of view optical structure is at least 150°.

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