Light and small large-view-field wide-spectrum imaging optical system suitable for being carried by unmanned aerial vehicle

Abstract

The invention discloses a light and small large-view-field wide-spectrum imaging optical system suitable for being carried by an unmanned aerial vehicle, and relates to the technical field of optical system imaging. The optical system comprises a front group optical system with negative focal power, an aperture diaphragm and a rear group optical system with positive focal power which are sequentially arranged from an object space to an image space along an optical axis direction, the front-group optical system consists of a first lens with negative focal power, a second lens with negative focal power and a third lens with positive focal power; and the rear group optical system consists of a fourth lens with positive focal power, a fifth lens with negative focal power, a sixth lens with negative focal power and a seventh lens with a negative light angle. According to the invention, the optical surfaces of all the lenses adopt spherical design, and the lenses are reasonably matched by utilizing the characteristics of the structures of all the lenses, so that the lens has the characteristics of wide shooting range, wide working wave band, high imaging quality, high relative illumination, good image surface uniformity, small volume, loose processing and adjustment tolerance and the like.

Description

Technical Field

[0001] The present invention relates to the field of optical system imaging technology, and in particular to a light, small, large-field-of-view, wide-spectrum imaging optical system suitable for being carried by an unmanned aerial vehicle. Background Art

[0002] With the rapid development of science and technology, drones are widely used in reconnaissance and monitoring, aerial photography, agricultural monitoring, disaster monitoring and other fields. The optical imaging system is one of the core components of drone equipment. It directly undertakes the task of obtaining target information, and its imaging resolution directly affects the working performance of drone equipment.

[0003] At present, in order to obtain clearer images throughout the day, people have put forward higher and higher requirements for the optical imaging systems used in drones, such as lightweight, large field of view and wide spectrum. These design requirements directly lead to the structure of the optical imaging system becoming relatively complex, the aberration of the optical system is relatively serious and difficult to correct, resulting in insufficient resolution of the imaging optical system; therefore, providing an imaging optical system for drones with high imaging quality, simple structure and miniaturization has very important practical application and promotion value. Summary of the invention

[0004] The purpose of the present invention is to propose a lightweight, large-field-of-view, wide-spectrum imaging optical system suitable for unmanned aerial vehicles to solve the problems raised in the background technology. Compared with the existing design, the present invention has the characteristics of wide shooting range, wide working band, high imaging quality, high relative illumination, good image surface uniformity, small size, and loose processing and assembly tolerances.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention is based on the fact that the aberration correction of the large field of view and wide spectrum imaging optical system is difficult and it has the imaging characteristics of the plane symmetrical optical system. Therefore, the optical system is divided into a front optical system and a rear optical system. Then, the wave aberration calculation expression of the plane symmetrical optical system is used to calculate various types of wave aberrations of the front optical system and the rear optical system, and the system total wave aberration balance equation is established, and then the balance equation is solved to obtain the optical system structural parameters; finally, the optical design software is used to establish the system aberration optimization evaluation function, and the aberration is continuously optimized. Finally, a large field of view and wide spectrum optical system suitable for unmanned aerial vehicles is designed. In the design process, the optical surfaces of all lenses are spherical, and finally a large-aperture zoom objective with good imaging quality is achieved, which specifically includes the following contents:

[0007] The optical system comprises a front optical system with negative optical power, an aperture stop, and a rear optical system with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis direction;

[0008] The front optical system is composed of a first lens with negative optical power, a second lens with negative optical power and a third lens with positive optical power;

[0009] The rear optical system consists of a fourth lens with positive optical power, a fifth lens with negative optical power, a sixth lens with negative optical power and a seventh lens with negative optical angle.

[0010] Preferably, the optical surfaces of the first lens facing the object side and the image side are both convex toward the object side;

[0011] The optical surface of the second lens facing the object side is convex toward the image side, and the optical surface facing the image side is convex toward the object side;

[0012] The optical surface of the third lens facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side;

[0013] The optical surface of the fourth lens facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side;

[0014] The optical surface of the fifth lens facing the object side is a plane, and the optical surface facing the image side is convex toward the object side;

[0015] The optical surface of the sixth lens facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side;

[0016] The optical surfaces of the seventh lens facing the object side and the image side are both convex toward the image side.

[0017] Preferably, the optical surfaces of each lens in the optical system facing the object side and the image side are spherical surfaces.

[0018] Preferably, the fourth lens and the fifth lens are glued together; the sixth lens and the seventh lens are glued together; and the aperture stop is located between the third lens and the fourth lens.

[0019] Preferably, the optical system has a maximum field of view of 140°, a total focal length of 1.04, an F / # value of 5.5, a total length of 23.62 mm, and a detectable wavelength range of 400 nm to 1100 nm.

[0020] Preferably, the material of the first lens, the second lens and the third lens are all SFL6, whose refractive index is 1.805182 and the Abbe number is 25.39; the material of the fourth lens and the seventh lens are all SF59, whose refractive index is 1.952497 and the Abbe number is 20.36; the material of the fifth lens is SF57, whose refractive index is 1.846663 and the Abbe number is 23.83; the material of the sixth lens is SK2, whose refractive index is 1.607381 and the Abbe number is 56.65.

[0021] Compared with the prior art, the present invention provides a lightweight, large-field-of-view, wide-spectrum imaging optical system suitable for use on unmanned aerial vehicles, which has the following beneficial effects:

[0022] The present invention proposes a light, small, large-field-of-view, wide-spectrum imaging optical system suitable for unmanned aerial vehicles, which is divided into a front optical system and a rear optical system; then, the wave aberration calculation expression of the plane symmetrical optical system is used to calculate the various wave aberrations of the front optical system and the rear optical system, and the system total wave aberration balance equation is established, and then the balance equation is solved to obtain the optical system structural parameters; finally, the optical design software is used to establish the system aberration optimization evaluation function, and the aberration is continuously optimized. Compared with the prior art, the present invention has the characteristics of wide shooting range, wide working band, high imaging quality, high relative illumination, good image surface uniformity, small size, and loose processing and assembly tolerance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings involved in the embodiments are briefly introduced. Obviously, the drawings in the following description are only schematic illustrations of some embodiments of the present invention. For those skilled in the art, other forms of drawings can also be constructed based on these drawings without creative work.

[0024] Figure 1 It is a structural schematic diagram of a light and small-sized, large-field-of-view, wide-spectrum imaging optical system suitable for use on a drone according to an embodiment of the present invention;

[0025] Figure 2 is based on Figure 1 The MTF curve of a light and small-sized large-field-of-view wide-spectrum imaging optical system suitable for UAVs is shown;

[0026] Figure 3 is based on Figure 1 A relative illumination diagram of a light and small-sized, large-field-of-view, wide-spectrum imaging optical system suitable for use on UAVs is shown;

[0027] Figure 4 is based on Figure 1The optical path diagram of a lightweight, large-field-of-view, wide-spectrum imaging optical system suitable for use on unmanned aerial vehicles is shown.

[0028] Description of the numbers in the figure:

[0029] G1, front optical system; L1, first lens; L2, second lens; L3, third lens;

[0030] G2, rear optical system; L4, the 4th lens; L5, the 5th lens; L6, the 6th lens; L7, the 7th lens. DETAILED DESCRIPTION

[0031] The following is a clear and comprehensive description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. It should be noted that the embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In order to make the above-mentioned objects, features and advantages of the present invention more clear, the technical solution of the present invention is described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0033] Embodiment 1:

[0034] like Figure 1 and Figure 4As shown, a light and small-sized large-field-of-view wide-spectrum imaging optical system suitable for being carried by an unmanned aerial vehicle comprises, along the direction of the optical axis, a front optical system G1 with negative optical power and a rear optical system G2 with positive optical power, which are arranged in sequence from the object side to the image side; the front optical system G1 is composed of a first lens L1 with negative optical power, a second lens L2 with negative optical power and a third lens L3 with positive optical power; the rear optical system G2 is composed of a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, a sixth lens L6 with positive optical power and a seventh lens L7 with negative optical power; the aperture stop is located between the third lens L3 and the fourth lens L4; wherein the fourth lens L4 and the fifth lens L5 are double-cemented lenses, and the sixth lens L6 and the seventh lens L7 are also double-cemented lenses. The optical surfaces of each lens in the optical system facing the object side and the image side are all spherical surfaces; the maximum field angle of the optical system is 140°, the total focal length is 1.04, the F / # value is 5.5, the total length is 23.62mm, and the detectable wavelength range is 400nm-1100nm; the materials of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6 and the seventh lens L7 are SFL6 (refractive index is 1.805182, Abbe number is 2 5.39), SFL6 (refractive index is 1.805182, Abbe number is 25.39), SFL6 (refractive index is 1.805182, Abbe number is 25.39), SF59 (refractive index is 1.952497, Abbe number is 20.36), SF57 (refractive index is 1.846663, Abbe number is 23.83), SK2 (refractive index is 1.607381, Abbe number is 56.65) and SF59 (refractive index is 1.952497, Abbe number is 20.36).

[0035] Figure 2 and Figure 3 They are the MTF curve and relative illumination curve of a lightweight, large-field-of-view, wide-spectrum imaging optical system suitable for UAVs. Figure 2 and Figure 3 The aberration correction in the light, small, large-field-of-view, wide-spectrum imaging optical system suitable for unmanned aerial vehicles that the present invention claims to protect is relatively good, and has the characteristics of good optical imaging performance and high relative illumination.

[0036] In order to facilitate understanding of the above technical solution, the usage of the proposed optical system is further explained below. The specific contents are as follows.

[0037] A light and small-sized large-field-of-view wide-spectrum imaging optical system suitable for being carried by an unmanned aerial vehicle comprises, along the direction of an optical axis, a front optical system G1 with negative optical power and a rear optical system G2 with positive optical power, which are arranged in sequence from the object side to the image side; the front optical system G1 is composed of a first lens L1 with negative optical power, a second lens L2 with negative optical power and a third lens L3 with positive optical power; the rear optical system G2 is composed of a fourth lens L4 with positive optical power, a fifth lens L5 with negative optical power, a sixth lens L6 with positive optical power and a seventh lens L7 with negative optical power; and an aperture stop is located between the third lens L3 and the fourth lens L4. The optical surfaces of the first lens L1 facing the object side and the image side are both convex toward the object side; the optical surface of the second lens L2 facing the object side is convex toward the image side, and the optical surface facing the image side is convex toward the object side; the optical surface of the third lens L3 facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side; the optical surface of the fourth lens L4 facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side; the optical surface of the fifth lens L5 facing the object side is a plane, and the optical surface facing the image side is convex toward the object side; the optical surface of the sixth lens L6 facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side; the optical surfaces of the seventh lens L7 facing the object side and the image side are both convex toward the image side.

[0038] The optical structural parameters of a lightweight, large-field-of-view, wide-spectrum imaging optical system suitable for use on unmanned aerial vehicles in this embodiment are shown in Table 1.

[0039] Table 1 Optical structural parameters of a lightweight, large-field-of-view, wide-spectrum imaging optical system suitable for UAVs

[0040] Optical Surface Radius(mm) Thickness(mm) Refractive Index Material S1 5.85 1.619 1.805182 SFL6 S2 2.467 2.793 S3 -4.367 1.266 1.805182 SFL6 S4 4.479 0.643 S5 19.913 1.001 1.805182 SFL6 S6 -5.24 10.049 Aperture stop unlimited 0.194 S7 4.671 0.337 1.952497 SF59 S8 unlimited 0.422 1.846663 SF57 S9 103.392 0.500 S10 3.447 0.688 1.607381 SK2 S11 -1.602 0.635 1.952497 SF59 S12 -9.003 3.477 S13 (image plane) unlimited -

[0041] In the above table, along the optical axis from the object plane to the image plane, S1 and S2 correspond to the optical surfaces of the first lens L1 facing the object side and the image side respectively; S3 and S4 correspond to the optical surfaces of the second lens L2 facing the object side and the image side respectively; S5 and S6 correspond to the optical surfaces of the third lens L3 facing the object side and the image side respectively; S7 and S8 correspond to the optical surfaces of the fourth lens L4 facing the object side and the image side respectively; S8 and S9 correspond to the optical surfaces of the fifth lens L5 facing the object side and the image side respectively; S10 and S11 correspond to the optical surfaces of the sixth lens L6 facing the object side and the image side respectively; S11 and S12 correspond to the optical surfaces of the seventh lens L7 facing the object side and the image side respectively; S13 corresponds to the image plane of the system. Among them, the 4th lens L4 and the 5th lens L5 are glued together, so S8 is both the optical surface of the 4th lens L4 facing the image side, and the optical surface of the 5th lens L5 facing the object side; the 6th lens L6 and the 7th lens L7 are glued together, so S11 is both the optical surface of the 6th lens L6 facing the image side, and the optical surface of the 7th lens L7 facing the object side.

[0042] In summary, with the aid of the above technical solution of the invention, the lens can have a wide shooting range, a wide working band, high imaging quality, high relative illumination, good image surface uniformity, a small size, and loose processing and assembly tolerances.

[0043] The remaining technical features in this embodiment can be flexibly selected by those skilled in the art according to actual conditions to meet different specific practical needs. However, it is obvious to those of ordinary skill in the art that it is not necessary to adopt these specific details to implement the present invention. In other examples, in order to avoid confusing the present invention, the composition, structure or components of the formula are not specifically described, and they are all within the technical protection scope defined by the technical solution claimed for protection in the claims of the present invention.

[0044] Modifications and changes made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the scope of protection of the claims attached to the present invention. In the above description, a large number of specific details are set forth in order to provide a thorough understanding of the present invention. However, it is obvious to those of ordinary skill in the art that these specific details are not necessary to practice the present invention. In other examples, in order to avoid confusing the present invention, well-known technologies, such as specific construction details, operating conditions and other technical conditions, are not specifically described.

[0045] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A light and small-sized, large-field-of-view, wide-spectrum imaging optical system suitable for use on UAVs, characterized in that: The optical system comprises a front optical system (G1) with negative optical power, an aperture stop, and a rear optical system (G2) with positive optical power, which are arranged in sequence from the object side to the image side along the optical axis direction; The front optical system (G1) is composed of a first lens (L1) with negative optical power, a second lens (L2) with negative optical power, and a third lens (L3) with positive optical power; The rear optical system (G2) is composed of a fourth lens (L4) with positive optical power, a fifth lens (L5) with negative optical power, a sixth lens (L6) with negative optical power and a seventh lens (L7) with a negative optical angle.

2. The light and small-sized large-field-of-view wide-spectrum imaging optical system suitable for use on unmanned aerial vehicles according to claim 1, characterized in that: The optical surfaces of the first lens (L1) facing the object side and the image side are both convex toward the object side; The optical surface of the second lens (L2) facing the object side is convex toward the image side, and the optical surface facing the image side is convex toward the object side; The optical surface of the third lens (L3) facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side; The optical surface of the fourth lens (L4) facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side; The optical surface of the fifth lens (L5) facing the object side is a plane, and the optical surface facing the image side is convex toward the object side; The optical surface of the sixth lens (L6) facing the object side is convex toward the object side, and the optical surface facing the image side is convex toward the image side; The optical surfaces of the seventh lens (L7) facing the object side and the image side are both convex toward the image side.

3. The light and small-sized large-field-of-view wide-spectrum imaging optical system suitable for use on unmanned aerial vehicles according to claim 1, characterized in that: The optical surfaces of each lens in the optical system facing the object side and the image side are all spherical surfaces.

4. The light and small-sized large-field-of-view wide-spectrum imaging optical system suitable for use on unmanned aerial vehicles according to claim 1, characterized in that: The fourth lens (L4) and the fifth lens (L5) are glued together; the sixth lens (L6) and the seventh lens (L7) are glued together; and the aperture stop is located between the third lens (L3) and the fourth lens (L4).

5. The light and small-sized large-field-of-view wide-spectrum imaging optical system suitable for use on unmanned aerial vehicles according to claim 1, characterized in that: The optical system has a maximum field angle of 140°, a total focal length of 1.04, an F / # value of 5.5, a total length of 23.62 mm, and a detectable wavelength range of 400 nm to 1100 nm.

6. The light and small-sized, large-field-of-view, wide-spectrum imaging optical system suitable for use on unmanned aerial vehicles according to claim 1, characterized in that: The materials of the first lens (L1), the second lens (L2) and the third lens (L3) are all SFL6, whose refractive index is 1.805182 and the Abbe number is 25.39; the materials of the fourth lens (L4) and the seventh lens (L7) are all SF59, whose refractive index is 1.952497 and the Abbe number is 20.36; the material of the fifth lens (L5) is SF57, whose refractive index is 1.846663 and the Abbe number is 23.83; the material of the sixth lens (L6) is SK2, whose refractive index is 1.607381 and the Abbe number is 56.65.

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