CN203909386U - special underwater imaging wide-angle lens - Google Patents

Abstract

The utility model proposes an underwater special imaging wide-angle lens, which includes a front negative group lens and a rear positive group lens located on the same optical path as the front negative group lens. Both the front negative group lens and the rear positive group lens include at least four spherical mirror. The utility model underwater special-purpose imaging wide-angle lens realizes real-time monitoring and shooting of underwater shooting horizontal field of view ≥ 75°, vertical field of view ≥ 60°, and diagonal field of view ≥ 85.3°.

Description

Underwater special imaging wide-angle lens

technical field

The utility model relates to the field of optics, in particular to a special wide-angle optical imaging system used in harsh underwater environments.

Background technique

With the continuous development of underwater detection technology, it is urgent to monitor the process of launching multiple targets from multiple angles and large field of view, so as to further understand the movement of moving targets during launching and understand the changes in the surrounding environment of moving targets.

The underwater imaging lens usually used can only monitor the moving target within a small field of view in real time or take small-angle shooting, and the applicable occasions are limited. For real-time monitoring of the launching motion state of an underwater high-speed moving target, a large field of view, large Relative aperture underwater dedicated imaging objective.

Utility model content

In order to solve the technical problems existing in the background technology, the utility model proposes a special underwater imaging wide-angle lens, which realizes underwater shooting with a horizontal field of view ≥ 75°, a vertical field of view ≥ 60°, and a diagonal field of view ≥85.3° real-time monitoring and shooting.

The technical solution of the utility model is: underwater special imaging wide-angle lens, including the front negative group lens and the rear positive group lens located on the same optical path as the front negative group lens, characterized in that: the front negative group lens and the rear positive group lens All include at least four spherical mirrors located on the same optical path.

The above-mentioned front negative lens group includes an optical window, a first negative lens, a second negative lens, a first positive lens, and a third negative lens that are sequentially positioned on the same optical path; the rear positive lens group includes a second positive lens that is sequentially positioned on the same optical path , the fourth negative lens, the third positive lens, the fourth positive lens, and the fifth positive lens.

The maximum effective aperture of the above lens is 130mm, the F number is 1.6, and the total length of the lens is 198mm;

The above-mentioned optical window is a concentric circular window of quartz glass.

The utility model has the advantages of high degree of automation, fast focusing speed, good imaging, large aperture, many lens groups, large room for selection and the like. Through such a structural layout, not only can effective control of off-axis aberrations be achieved, but also a larger back focus can be achieved under the premise of a small focal length. In addition, more glass with high refractive index and low dispersion is used to correct the spherical aberration caused by the large aperture. The lens of the utility model realizes real-time monitoring and shooting of underwater shooting with a horizontal field of view ≥ 75°, a vertical field of view ≥ 60°, and a diagonal field of view ≥ 85.3°.

Description of drawings

Fig. 1 is a schematic diagram of the principle of the utility model;

Fig. 2 is a structural representation of the utility model;

Fig. 3 is the optical transfer function figure of the utility model optical system;

Fig. 4 is an optical transfer function diagram with an infinite object distance of 5 meters;

Fig. 5 is an optical transfer function diagram with an infinite object distance of 0.5 meters;

Detailed ways

As shown in Figure 1, the underwater special imaging wide-angle lens of the utility model adopts a reflective telephoto structure, which is composed of a front negative group lens 1 and a rear positive group lens 2, and the optical window 3 is a concentric circular window made of quartz glass. , this type of window has less field of view loss than flat windows, reliable performance, and strong pressure resistance. Its disadvantage is that it has high requirements for processing and assembly technology, and high maintenance cost, so it has been widely used in related projects in the past. Practice shows that this kind of sealing window is reasonable and feasible.

Figure 2 is a structural diagram of the optical system, using 10 spherical mirrors located in the same optical path; the front negative lens group 1 includes an optical window 3, a first negative lens 4, a second negative lens 5, a first positive lens 6, and a third negative lens 7 The rear positive group lens 2 includes the second positive lens 8, the fourth negative lens 9, the third positive lens 10, the fourth positive lens 11, and the fifth positive lens 12 that are positioned on the same optical path in turn; the maximum effective aperture of the lens is 130mm, and the F number It is 1.6; the total length of the lens is 198mm.

Figure 3 is the MTF diagram of the optical system. MTF represents the ability of the optical system to transmit the contrast of the target. The higher the value, the better the aberration control. Since the smallest pixel of CCD is 22μm, its corresponding spatial frequency is 23lp/mm. In order to match the optical system with CCD, the actual investigation must be carried out at the spatial frequency of 23lp/mm. As shown in Figure 3, the MTF of the field of view of 0.707 at this spatial frequency is higher than the minimum process requirement value of 0.3, which can meet the actual work requirements.

The optical system is designed for infinity, but in actual use it is a finite distance. In order to meet the imaging definition of limited distance, the lens must be able to adjust the focus. Since the spherical shell window itself has a focal power, the window cannot be moved during actual use, so the entire lens group cannot be moved when focusing. The structure of this lens adopts the structure of the front and rear lens groups, the focal length of the front group is negative, and the focal length of the rear group is positive. The lens focus can be realized by changing the distance between the rear group and the front group. Figures 4 and 5 are the optical transfer function diagrams when the infinite object distance is 5 meters and 0.5 meters respectively, and the movement amounts of the rear group are 0.092mm and 0.25mm respectively.

In actual use, it is only necessary to seal the special underwater imaging wide-angle lens in the airtight housing, and then place the system in the target area to be measured to complete real-time monitoring and shooting. The optical system is simple and practical, easy to operate, and can complete underwater large-angle monitoring and shooting in real time.

Claims (3)

1. Underwater special-purpose imaging wide-angle lens, comprise front negative group lens and the back positive group lens that is positioned at the same optical path with front negative group lens, it is characterized in that: described front negative group lens and rear positive group lens all comprise at least four are positioned at the same The spherical mirror of the optical path; the front negative lens group includes an optical window, the first negative lens, the second negative lens, the first positive lens, and the third negative lens that are sequentially located in the same optical path; the rear positive lens group includes sequentially located in the same optical path The second positive lens, the fourth negative lens, the third positive lens, the fourth positive lens, and the fifth positive lens. the 2. The special underwater imaging wide-angle lens according to claim 1, characterized in that: the maximum effective diameter of the lens is 130 mm, the F number is 1.6, and the total length of the lens is 198 mm. the 3. The special underwater imaging wide-angle lens according to claim 2, characterized in that: the optical window is a concentric circular window made of quartz glass. the