Ultra-wide-angle large-relative-aperture amphibious optical system

Abstract

The invention relates to an optical system, in particular to an ultra-wide-angle large-relative-aperture amphibious optical system, and solves the problems that an existing optical system is difficult to have an ultra-large view field and a large relative aperture on the premise that the requirement for water and land multiplexing is met, the system guiding and imaging effects are poor, and the machining difficulty is large. According to the invention, a dome cover window is used as a protection window, and underwater and onshore states are comprehensively designed by using the same parameters, so that the whole system realizes water and land reuse on the premise of not needing additional adjustment; through the parameter design of each lens, the overall size of the system is reduced, and the processing difficulty is reduced; the whole system has an ultra-wide field of view and a large relative aperture underwater, the signal presentation and processing effect in the guiding process is improved, the guiding precision is improved, the system also has the characteristics of the ultra-large field of view and the large relative aperture when imaging in the air, the imaging quality is good, and the large-range monitoring image effect is effectively improved.

Description

Technical Field

[0001] The present invention relates to an optical system, in particular to an ultra-wide-angle, large relative aperture, amphibious optical system. Background Art

[0002] With the continuous development of marine science and technology, underwater unmanned platforms such as autonomous underwater vehicles (AUVs) are playing an increasingly important role in fields such as marine environmental observation, marine resource development, and underwater engineering and operations due to their unmanned operation and ability to sense and provide feedback. To improve the quality and efficiency of underwater missions, underwater vehicles require precise position information during navigation, making underwater guidance technology an indispensable tool. Underwater optical guidance technology uses optical sensors such as underwater cameras to obtain image information of the target and utilizes image processing and analysis techniques to provide the underwater vehicle with position, attitude, and other information. Compared to other guidance technologies such as underwater acoustic guidance, it offers high precision, large amounts of information, and strong reliability in close-range applications, making it the optimal choice for close-range guidance.

[0003] On the other hand, monitoring targets above the water surface also plays a multifaceted role in underwater guidance. It helps monitor changes in the above-water working environment and provides underwater platforms with real-time dynamic information about the surrounding waters. By continuously tracking and analyzing the trajectory of surface targets, future locations and trends can be predicted, allowing for the planning of underwater equipment routes. For example, drones can be used to capture images of targets above the water surface, providing support for underwater equipment route planning.

[0004] To achieve the above-mentioned underwater optical guidance and surface target monitoring, the transmission and presentation of target information by the optical system is indispensable. In order to save costs and improve the convenience of switching between underwater and land operations, it is necessary to develop an optical system that can be used for both underwater guidance and land target monitoring. Under the premise of meeting the needs of water and land reuse, in order to expand the scope of underwater guidance and land target monitoring, the optical system needs to have an ultra-large field of view and a large relative aperture. At the same time, in order to improve the accuracy of underwater guidance and land target monitoring, the system also needs to have small spot differences under different fields of view underwater and high imaging resolution in the air. In addition, in order to better adapt to underwater and land-based platforms, the total length and aperture of the optical system should be as small as possible. In order to reduce the difficulty and cost of system processing, the system also needs to reduce the number of lenses and strictly control the lens parameters, which brings great difficulties and challenges to the design of the optical system. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that existing optical systems are difficult to have an ultra-large field of view and a large relative aperture while meeting the requirements of amphibious reuse, as well as the technical problems of poor system guidance and imaging effects and high processing difficulty, and to provide an ultra-wide-angle, large relative aperture amphibious optical system.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] An ultra-wide-angle, large relative aperture amphibious optical system, its special features are:

[0008] It includes a ball cover window, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a cemented lens, a sixth lens and a detector which are sequentially arranged along the optical path;

[0009] The first lens is a meniscus lens with negative optical power, and its incident surface is convex; the second lens is a meniscus lens with negative optical power, and its incident surface is convex; the third lens is a meniscus lens with positive optical power, and its incident surface is concave; the fourth lens is a biconvex lens with positive optical power, and the fifth lens is a meniscus lens with positive optical power, wherein the incident surface is convex; the cemented lens has positive optical power, and includes a cemented lens 1 and a cemented lens 2 arranged in sequence along the optical path, the cemented lens 1 is a biconvex lens with positive optical power, the cemented lens 2 is a meniscus lens with negative optical power, and the incident surface of the cemented lens 2 is concave; the sixth lens is a meniscus lens with positive optical power, and its incident surface is convex;

[0010] The distance between the center of the exit surface of the ball cover window and the center of the incident surface of the first lens on the optical axis of the optical path is 6-17 mm; the distance between the center of the exit surface of the first lens and the center of the incident surface of the second lens on the optical axis of the optical path is 2.9-4.5 mm; the distance between the center of the exit surface of the second lens and the center of the incident surface of the third lens on the optical axis of the optical path is 5-6.5 mm; the distance between the center of the exit surface of the third lens and the center of the incident surface of the fourth lens on the optical axis of the optical path is 0.6-1.3 mm; the distance between the center of the exit surface of the fourth lens and the center of the incident surface of the fifth lens on the optical axis of the optical path is 0.3-1 mm; the distance between the center of the exit surface of the fifth lens and the center of the incident surface of the cemented mirror on the optical axis of the optical path is 1.5-2.5 mm; the distance between the center of the exit surface of the cemented mirror and the center of the incident surface of the sixth lens on the optical axis of the optical path is 0.1-0.6 mm;

[0011] The dome window is a hemispherical dome, and the system preset clear aperture OA and the system preset effective focal length f satisfy:

[0012] 0.4 <OA / f<0.5

[0013] 1.1mm≤OA≤1.9mm.

[0014] Furthermore, the material of the ball cover window is H-K9L or N-BK7;

[0015] Under the premise of ensuring the pressure resistance characteristics, the system field of view can be improved and the manufacturing cost can be reduced;

[0016] The inner diameter BS1 of the spherical cover window and the thickness T1 of the spherical cover window satisfy:

[0017] 2.4 <BS1 / T1<7.2

[0018] 38mm≤BS1≤45mm;

[0019] Satisfying the above relationship ensures that the optical-mechanical characteristics of the window do not change underwater, effectively improving the system's pressure resistance;

[0020] The inner aperture BS1 of the dome window and the effective clear aperture SA1 of the incident surface of the first lens satisfy:

[0021] 8mm <BS1-SA1<29mm

[0022] Satisfying the above relationship improves the compatibility between the dome window and the rear lens, reducing installation difficulty;

[0023] The curvature radius R2 of the exit surface of the spherical cover window and the distance T12 between the center of the exit surface of the spherical cover window and the center of the incident surface of the first lens on the optical axis of the optical path satisfy:

[0024] 1.11 <R2 / T12<4.58

[0025] Satisfying the above relationship can reduce the impact of the refraction of the dome window on system performance, improve spherical aberration, coma and astigmatism, and narrow the geometric difference between air and underwater light.

[0026] Furthermore, the curvature radius CR1 of the incident surface of the first lens and the effective clear aperture SA1 of the incident surface of the first lens satisfy:

[0027] 0.75 <CR1 / SA1<1;

[0028] Satisfying the above relationship can reduce the processing difficulty and cost of the first lens and improve the energy transmittance of the first lens;

[0029] The curvature radius CR2 of the exit surface of the first lens and the effective clear aperture SA2 of the exit surface of the first lens satisfy:

[0030] 0.575 <CR2 / SA2<0.75

[0031] 10mm≤SA2≤22mm;

[0032] By satisfying the above relationship, the light transmission angle can be optimized so that the system light can better match the detector;

[0033] The curvature radius CR3 of the second lens exit surface and the effective clear aperture SA3 of the second lens exit surface satisfy:

[0034] 0.565 <CR3 / SA3<0.75

[0035] 8mm≤SA3≤20mm;

[0036] Satisfying the above relationship is beneficial to improving the processing and forming characteristics of the second lens and optimizing the focusing position of the light;

[0037] The curvature radius CR4 of the incident surface of the third lens and the effective clear aperture SA4 of the incident surface of the third lens satisfy:

[0038] -1.25 <CR4 / SA4<-0.75

[0039] 7mm≤SA4≤19mm;

[0040] Satisfying the above relationship can reduce the difficulty of processing the third lens and reduce the influence of stray light caused by the exit surface of the first lens;

[0041] The curvature radius CR5 of the exit surface of the fifth lens and the effective clear aperture SA5 of the exit surface of the fifth lens satisfy:

[0042] 0.8 <CR5 / SA5<1.3

[0043] 3.6mm≤SA5≤7.2mm;

[0044] Satisfying the above relationship can reduce the difficulty of processing the fifth lens and improve the system's light convergence effect;

[0045] The curvature radius CR6 of the first exit surface of the cemented lens and the effective clear aperture SA6 of the first exit surface of the cemented lens satisfy:

[0046] 0.65 <CR6 / SA6<0.85

[0047] 3mm≤SA6≤5mm.

[0048] Satisfying the above relationship can reduce the manufacturing difficulty and cost of the first and second cemented lenses, and improve the illumination uniformity of the system image plane.

[0049] Furthermore, the distance TD between the incident surface of the first lens and the preset imaging surface of the system and the preset image surface size MTH of the system satisfy:

[0050] 2.7 <TD / MTH<5

[0051] 32mm≤TD≤40mm;

[0052] Satisfying the above relationship can effectively increase the image height while ensuring a short system length.

[0053] Furthermore, the curvature radius CR2 of the exit surface of the first lens and the edge distance ET12 between the first lens and the second lens satisfy:

[0054] 4.7 <CR2 / ET12<28

[0055] 0.35mm <ET12<1.5mm;

[0056] Satisfying the above relationship can increase the processing tolerance of each lens and reduce the assembly difficulty of the entire system;

[0057] The edge spacing ET23 between the second lens and the third lens and the edge spacing ET34 between the third lens and the fourth lens satisfy:

[0058] 0.15 <ET23 / ET34<0.8

[0059] 0.6mm <ET23<2mm。

[0060] By satisfying the above relationship, the length of the entire system can be controlled within a reasonable range, making the layout of each lens more reasonable.

[0061] Furthermore, the angle OG2 between the main ray of the edge field of view of the first lens exit surface and the normal of the surface and the angle OG4 between the main ray of the edge field of view of the second lens exit surface and the normal of the surface satisfy:

[0062] 0.23 <OG2 / OG4<0.36

[0063] 25° <OG4<30°;

[0064] Satisfying the above relationship helps prevent light from deviating too much from the optical axis on the side of the second lens exit surface, thereby enhancing the system's control over off-axis aberrations.

[0065] The angle IG5 between the incident principal ray of the edge field of view of the incident surface of the third lens and the normal of the surface and the angle IG6 between the incident principal ray of the edge field of view of the exit surface of the fourth lens and the normal of the surface satisfy:

[0066] 1.75 <IG5 / IG6<2.81

[0067] 16° <IG6<20°。

[0068] By satisfying the above relationship, the degree to which the incident light on the incident surface of the third lens deviates from the optical axis can be controlled to be within a reasonable range, thereby reducing off-axis aberrations and improving light energy utilization.

[0069] Furthermore, the center thickness CT2 of the second lens and the center thickness CT3 of the third lens satisfy: 0.24 <CT2 / CT3<0.68

[0070] 2.8mm <CT3<5mm;

[0071] Satisfying the above relationship can reduce the difference in thickness between the second lens and the third lens, and is conducive to the reasonable distribution of the thickness of each lens in the system.

[0072] The center thickness CTS1 of the first cemented lens and the center thickness CTS2 of the second cemented lens satisfy:

[0073] 0.57 <CTS1 / CTS2<1.6

[0074] 2mm <CTS1<4mm。

[0075] Satisfying the above relationship can effectively reduce the system chromatic aberration and make the thickness distribution of the first cemented lens and the second cemented lens more reasonable.

[0076] Furthermore, the focal length f2 of the second lens and the focal length f4 of the fourth lens satisfy:

[0077] -1.14 <f2 / f4<-0.72

[0078] 14mm <f4<18mm;

[0079] Satisfying the above relationship is conducive to the reasonable distribution of the system's optical power and improves the system's ability to balance aberrations;

[0080] The focal length f5 of the fifth lens and the system preset effective focal length f satisfy:

[0081] 9.3 <f5 / f<24

[0082] 40mm <f5<60mm。

[0083] Satisfying the above relationship avoids excessive concentration of the system light focal length and further improves the light convergence effect.

[0084] Furthermore, the distance T67 between the effective clear aperture SA14 of the incident surface of the sixth lens and the center of the exit surface of the cemented lens and the center of the incident surface of the sixth lens on the optical axis of the optical path satisfies:

[0085] 10 <SA14 / T67<80

[0086] 6mm <SA14<8mm;

[0087] Satisfying the above relationship effectively reduces the lens aperture and reduces the difficulty of system assembly and adjustment;

[0088] The distance T2 between the center of the exit surface of the sixth lens and the preset imaging plane of the system on the optical axis of the optical path satisfies:

[0089] 3mm <T2<6mm。

[0090] Satisfying the above relationship reduces the difficulty of detector installation and adjustment, which is beneficial to improving the system performance.

[0091] Furthermore, it also includes an aperture stop, which is located between the fifth lens and the cemented lens.

[0092] It is beneficial to increase the system's field of view, constrain distortion, and control the aperture of each lens within a smaller range.

[0093] Compared with the prior art, the present invention has the following beneficial effects:

[0094] The present invention provides an ultra-wide-angle, large relative aperture amphibious optical system. By setting a spherical cover window as a protective window and using the same parameters to comprehensively design the underwater and onshore states, the entire system can be reused on land and water without additional adjustments. Through the reasonable design of the parameters of each lens, the overall size of the system is reduced, and the processing difficulty is reduced. The entire system has the characteristics of an ultra-wide-angle field of view and a large relative aperture both underwater and on land, which effectively improves the signal presentation and processing effects in the guidance process, improves the guidance accuracy, and can effectively improve the signal presentation and processing effects in the large-scale guidance process. When imaging in the air, it also has the characteristics of an ultra-large field of view and a large relative aperture, and the imaging quality is good, which effectively improves the large-scale monitoring picture effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0095] Figure 1 This is an optical path diagram of an embodiment of an ultra-wide-angle, large relative aperture amphibious optical system according to the present invention;

[0096] Figure 2 This is a spot diagram of an embodiment of the present invention when the object distance is 0.5 m and the object medium is seawater;

[0097] Figure 3 This is a spot diagram of an embodiment of the present invention when the object distance is 3m and the object medium is seawater;

[0098] Figure 4 This is a spot diagram of an embodiment of the present invention when the object distance is 20m and the object medium is seawater;

[0099] Figure 5 This is an MTF curve diagram of an embodiment of the present invention when the object distance is 5m and the object medium is air;

[0100] Figure 6This is an MTF curve diagram of an embodiment of the present invention when the object distance is 50m and the object medium is air;

[0101] Figure 7 This is an MTF curve diagram of an embodiment of the present invention when the object distance is infinite and the object medium is air.

[0102] The following are the descriptions of the reference numerals:

[0103] 1-ball cover window, 2-first lens, 3-second lens, 4-third lens, 5-fourth lens, 6-fifth lens, 7-cemented lens, 71-cemented lens 1, 72-cemented lens 2; 8-sixth lens, 9-aperture stop, 10-detector. DETAILED DESCRIPTION

[0104] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.

[0105] Reference Figure 1 The present invention provides an ultra-wide-angle, large relative aperture amphibious optical system comprising a dome window 1, a first lens 2, a second lens 3, a third lens 4, a fourth lens 5, a fifth lens 6, a cemented mirror 7, a sixth lens 8, and a detector 10, which are sequentially arranged along the optical path. An aperture stop 9 is also provided between the fifth lens 6 and the cemented mirror 7. To meet the requirements of amphibious applications, the dome window 1 is provided, and a reverse telephoto structure is used as the basis. Multiple structures are set up for the two working media of water and air, and the two wavelength bands of blue light (430nm to 470nm) and visible light (486nm to 656nm). The field of view type is selected as the angle, the maximum aperture and length of the lens group are controlled, and the system's focus spot underwater and imaging effect in the air are optimized to obtain the final design.

[0106] The technical indicators of this embodiment are shown in Table 1:

[0107] Table 1

[0108]

[0109] Among them, the first lens 2 is a meniscus lens with negative optical focal length, and its incident surface is convex; the second lens 3 is a meniscus lens with negative optical focal length, and its incident surface is convex; the third lens 4 is a meniscus lens with positive optical focal length, and its incident surface is concave; the fourth lens 5 is a biconvex lens with positive optical focal length; the fifth lens 6 is a meniscus lens with positive optical focal length, and its incident surface is convex; the cemented lens 7 has positive optical focal length, including a cemented lens 1 71 and a cemented lens 2 72 arranged in sequence along the optical path; the cemented lens 1 71 is a biconvex lens with positive optical focal length, the cemented lens 2 72 is a meniscus lens with negative optical focal length, and the incident surface of the cemented lens 2 72 is concave; the sixth lens 8 is a meniscus lens with positive optical focal length, and its incident surface is convex. After passing through the first lens 2, the second lens 3 and the third lens 4, the light beam diverges and converges after passing through the remaining lenses. This design effectively expands the field of view and reduces the system aberration.

[0110] Detector 10 uses the Maide Satellite TV MV-GE300GC industrial camera with a pixel size of 3.45 microns, a resolution of 2048*1536, a diagonal size of 8.8mm, and an imaging height of 8.8mm in the air. It achieves a high degree of matching with the camera target surface, and the underwater imaging height matching also reaches a high level, which is conducive to ensuring the field of view of the system and effectively improving the underwater spot detection accuracy and imaging effect in the air.

[0111] Dome window 1 is a hemispherical dome made of H-K9L or N-BK7. With dome window 1 installed, the system can operate at a depth of up to 500m. The incident surface of dome window 1 is uncoated, while the exit surface is coated with a 430nm-656nm antireflection coating. The incident and exit surfaces of the remaining lenses are both coated with a 430nm-656nm antireflection coating, achieving a transmittance greater than 99%. This coating enhances system energy efficiency, improves the detector 10's response to optical signals underwater and in air, and reduces the impact of stray light on received signals.

[0112] The distance between the center of the exit surface of the dome cover window 1 and the center of the incident surface of the first lens 2 on the optical axis of the optical path is 6-17 mm; the distance between the center of the exit surface of the first lens 2 and the center of the incident surface of the second lens 3 on the optical axis of the optical path is 2.9-4.5 mm; the distance between the center of the exit surface of the second lens 3 and the center of the incident surface of the third lens 4 on the optical axis of the optical path is 5-6.5 mm; the distance between the center of the exit surface of the third lens 4 and the center of the incident surface of the fourth lens 5 on the optical axis of the optical path is 0.6-1.3 mm; the distance between the center of the exit surface of the fourth lens 5 and the center of the incident surface of the fifth lens 6 on the optical axis of the optical path is 0.3-1 mm; the distance between the center of the exit surface of the fifth lens 6 and the center of the incident surface of the cemented lens 7 on the optical axis of the optical path is 1.5-2.5 mm; the distance between the center of the exit surface of the cemented lens 7 and the center of the incident surface of the sixth lens 8 on the optical axis of the optical path is 0.1-0.6 mm.

[0113] In this embodiment, the specific parameters of each lens are shown in Table 2:

[0114] Table 2

[0115]

[0116]

[0117] Note: In Table 2, lens refers to each lens in the system, curvature radius refers to the curvature radius of each lens optical surface, thickness refers to the center thickness of the lens or the thickness of the medium before and after the lens, material refers to the material brand used for the lens, and diameter refers to the corresponding aperture of each optical surface.

[0118] In the table above, the system's object surface (S0) is made of seawater, which is suitable for underwater applications. For onshore applications, the S0 surface material must be changed to air. A dome window 1 is positioned behind the S0 surface to protect the lens. The outer and inner diameters of the dome are 60mm and 40mm, respectively, reducing the overall system size while easing manufacturing complexity.

[0119] The system's focal length has been controlled to 2.88mm underwater and 4.01mm in air, with a relative aperture of 1 / 2.3, which can expand the system's field of view, increase the system's light throughput, and enhance the optical signal strength.

[0120] When the dome cover window 1 is included, the system has a maximum aperture of 60mm and an overall length of 64.3mm, effectively controlling the system size and facilitating deployment in multiple scenarios. Without the dome cover window 1, the maximum aperture is only 23.3mm and the overall length is only 39.3mm, facilitating lens assembly and improving adaptability to dome cover windows 1 of different specifications.

[0121] The surface type of all lenses is spherical, and they are combined with other single lenses through a cemented lens 7 to achieve chromatic aberration correction while reducing the difficulty of installation and engineering implementation.

[0122] In this embodiment, each lens has the following design requirements:

[0123] (1) The system preset clear aperture OA and the system preset effective focal length f meet the following requirements:

[0124] 0.4 <OA / f<0.5

[0125] 1.1mm≤OA≤1.9mm;

[0126] Satisfying the above relationship is beneficial to improving the system's light throughput and imaging resolution, and increasing the field of view.

[0127] (2) The inner diameter BS1 of the dome window 1 and the thickness T1 of the dome window 1 satisfy:

[0128] 2.4 <BS1 / T1<7.2

[0129] 38mm≤BS1≤45mm.

[0130] (3) The inner aperture BS1 of the dome window 1 and the effective aperture SA1 of the incident surface of the first lens 2 satisfy:

[0131] 8mm <BS1-SA1<29mm。

[0132] (4) The curvature radius R2 of the exit surface of the spherical cover window 1 and the distance T12 between the center of the exit surface of the spherical cover window 1 and the center of the incident surface of the first lens 2 on the optical axis of the optical path satisfy:

[0133] 1.11 <R2 / T12<4.58。

[0134] (5) The curvature radius CR1 of the incident surface of the first lens 2 and the effective aperture SA1 of the incident surface of the first lens 2 satisfy:

[0135] 0.75 <CR1 / SA1<1。

[0136] (6) The curvature radius CR2 of the exit surface of the first lens 2 and the effective aperture SA2 of the exit surface of the first lens 2 satisfy:

[0137] 0.575 <CR2 / SA2<0.75

[0138] 10mm≤SA2≤22mm.

[0139] (7) The curvature radius CR3 of the exit surface of the second lens 3 and the effective clear aperture SA3 of the exit surface of the second lens 3 satisfy:

[0140] 0.565 <CR3 / SA3<0.75

[0141] 8mm≤SA3≤20mm.

[0142] (8) The curvature radius CR4 of the incident surface of the third lens 4 and the effective clear aperture SA4 of the incident surface of the third lens 4 satisfy:

[0143] -1.25 <CR4 / SA4<-0.75

[0144] 7mm≤SA4≤19mm.

[0145] (9) The curvature radius CR5 of the exit surface of the fifth lens 6 and the effective clear aperture SA5 of the exit surface of the fifth lens 6 satisfy:

[0146] 0.8 <CR5 / SA5<1.3

[0147] 3.6mm≤SA5≤7.2mm.

[0148] (10) The curvature radius CR6 of the output surface of the cemented lens 71 and the effective aperture SA6 of the output surface of the cemented lens 71 satisfy:

[0149] 0.65 <CR6 / SA6<0.85

[0150] 3mm≤SA6≤5mm.

[0151] (11) The distance TD from the incident surface of the first lens 2 to the preset imaging surface of the system and the preset image surface size MTH of the system satisfy:

[0152] 2.7 <TD / MTH<5

[0153] 32mm≤TD≤40mm.

[0154] (12) The curvature radius CR2 of the exit surface of the first lens 2 and the edge distance ET12 between the first lens 2 and the second lens 3 satisfy:

[0155] 4.7 <CR2 / ET12<28

[0156] 0.5mm <ET12<1.5mm。

[0157] (13) The edge spacing ET23 between the second lens 3 and the third lens 4 and the edge spacing ET34 between the third lens 4 and the fourth lens 5 satisfy:

[0158] 0.15 <ET23 / ET34<0.8

[0159] 0.6mm <ET23<2mm。

[0160] (14) The angle OG2 between the main ray of the edge field of view of the exit surface of the first lens 2 and the normal of the surface and the angle OG4 between the main ray of the edge field of view of the exit surface of the second lens 3 and the normal of the surface satisfy:

[0161] 0.23 <OG2 / OG4<0.36

[0162] 25° <OG4<30°。

[0163] (15) The angle IG5 between the incident principal ray of the marginal field of view on the incident surface of the third lens 4 and the normal to the surface and the angle IG6 between the incident principal ray of the marginal field of view on the exit surface of the fourth lens 5 and the normal to the surface satisfy:

[0164] 1.75 <IG5 / IG6<2.81

[0165] 16° <IG6<20°。

[0166] (16) The center thickness CT2 of the second lens 3 and the center thickness CT3 of the third lens 4 satisfy:

[0167] 0.24 <CT2 / CT3<0.68

[0168] 2.8mm <CT3<5mm。

[0169] (17) The center thickness CTS1 of the cemented lens 1 71 and the center thickness CTS2 of the cemented lens 2 72 satisfy:

[0170] 0.57 <CTS1 / CTS2<1.6

[0171] 2mm <CTS1<4mm。

[0172] (18) The focal length f2 of the second lens 3 and the focal length f4 of the fourth lens 5 satisfy:

[0173] -1.14 <f2 / f4<-0.72

[0174] 14mm <f4<18mm;

[0175] (19) The focal length f5 of the fifth lens 6 and the system preset effective focal length f satisfy:

[0176] 9.3 <f5 / f<24

[0177] 40mm <f5<60mm。

[0178] (20) The effective clear aperture SA14 of the incident surface of the sixth lens 8 and the distance T67 between the center of the exit surface of the cemented mirror 7 and the center of the incident surface of the sixth lens 8 on the optical axis of the optical path satisfy:

[0179] 10 <SA14 / T67<80

[0180] 6mm <SA14<8mm。

[0181] (21) The distance T2 between the center of the exit surface of the sixth lens 8 and the preset imaging plane of the system on the optical axis of the optical path satisfies:

[0182] 3mm <T2<6mm。

[0183] from Figure 2-Figure 4 It can be seen that when working underwater, when the system is at an object distance of 0.5m, 3mm and 20m, the spot size formed in different fields of view is uniform and the shape consistency is high. In addition, the diameter of the focused spot in each field of view is greater than 34.5um (10 times the pixel), which improves the accuracy of extracting the position information of the underwater guidance spot and enhances the guidance effect.

[0184] from Figure 5-Figure 7 It can be seen that when working in the air, when the system is at an object distance of 5m, 50m, and infinite object distance, the resolution of different fields of view is better than 72lp / mm. The imaging resolution is good, ensuring that the system can obtain high image quality, which can meet the needs of land-based monitoring operations and is especially suitable for drone-mounted applications.

[0185] The embodiments described above are merely descriptions of specific implementation methods of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. An ultra-wide-angle, large relative aperture amphibious optical system, characterized by: It comprises a spherical cover window (1), a first lens (2), a second lens (3), a third lens (4), a fourth lens (5), a fifth lens (6), a cemented lens (7), a sixth lens (8) and a detector (10) which are sequentially arranged along the optical path; The first lens (2) is a meniscus lens with negative focal power, and its incident surface is convex; the second lens (3) is a meniscus lens with negative focal power, and its incident surface is convex; the third lens (4) is a meniscus lens with positive focal power, and its incident surface is concave; the fourth lens (5) is a biconvex lens with positive focal power, and the fifth lens (6) is a meniscus lens with positive focal power, wherein the incident surface is convex; the cemented lens (7) has positive focal power, and comprises a cemented lens 1 (71) and a cemented lens 2 (72) arranged in sequence along the optical path, the cemented lens 1 (71) is a biconvex lens with positive focal power, the cemented lens 2 (72) is a meniscus lens with negative focal power, and the incident surface of the cemented lens 2 (72) is concave; the sixth lens (8) is a meniscus lens with positive focal power, and its incident surface is convex; The distance between the center of the exit surface of the spherical cover window (1) and the center of the incident surface of the first lens (2) on the optical axis of the optical path is 6-17 mm; the distance between the center of the exit surface of the first lens (2) and the center of the incident surface of the second lens (3) on the optical axis of the optical path is 2.9-4.5 mm; the distance between the center of the exit surface of the second lens (3) and the center of the incident surface of the third lens (4) on the optical axis of the optical path is 5-6.5 mm; the distance between the center of the exit surface of the third lens (4) and the center of the incident surface of the fourth lens (5 .... The distance between the center of the exit surface and the center of the incident surface of the fifth lens (6) on the optical axis of the optical path is 0.6-1.3 mm; the distance between the center of the exit surface of the fourth lens (5) and the center of the incident surface of the fifth lens (6) on the optical axis of the optical path is 0.3-1 mm; the distance between the center of the exit surface of the fifth lens (6) and the center of the incident surface of the cemented lens (7) on the optical axis of the optical path is 1.5-2.5 mm; the distance between the center of the exit surface of the cemented lens (7) and the center of the incident surface of the sixth lens (8) on the optical axis of the optical path is 0.1-0.6 mm; The dome cover window (1) is a hemispherical cover, and the system preset clear aperture OA and the system preset effective focal length f satisfy: 0.4 <OA / f<0.5 1.1mm≤OA≤1.9mm.

2. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 1, characterized in that: The material of the ball cover window (1) is H-K9L or N-BK7; The inner diameter BS1 of the spherical cover window (1) and the thickness T1 of the spherical cover window (1) satisfy: 2.4 <BS1 / T1<7.2 38mm≤BS1≤45mm; The inner aperture BS1 of the spherical cover window (1) and the effective light aperture SA1 of the incident surface of the first lens (2) satisfy: 8mm <BS1-SA1<29mm The curvature radius R2 of the exit surface of the spherical cover window (1) and the distance T12 between the center of the exit surface of the spherical cover window (1) and the center of the incident surface of the first lens (2) on the optical axis of the optical path satisfy: 1.11 <R2 / T12<4.58。 3. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 2, characterized in that: The curvature radius CR1 of the incident surface of the first lens (2) and the effective clear aperture SA1 of the incident surface of the first lens (2) satisfy: 0.75 <CR1 / SA1<1; The curvature radius CR2 of the exit surface of the first lens (2) and the effective clear aperture SA2 of the exit surface of the first lens (2) satisfy: 0.575 <CR2 / SA2<0.75 10mm≤SA2≤22mm; The curvature radius CR3 of the exit surface of the second lens (3) and the effective clear aperture SA3 of the exit surface of the second lens (3) satisfy: 0.565 <CR3 / SA3<0.75 8mm≤SA3≤20mm; The curvature radius CR4 of the incident surface of the third lens (4) and the effective clear aperture SA4 of the incident surface of the third lens (4) satisfy: -1.25 <CR4 / SA4<-0.75 7mm≤SA4≤19mm; The curvature radius CR5 of the exit surface of the fifth lens (6) and the effective clear aperture SA5 of the exit surface of the fifth lens (6) satisfy: 0.8 <CR5 / SA5<1.3 3.6mm≤SA5≤7.2mm; The curvature radius CR6 of the output surface of the cemented lens (71) and the effective light aperture SA6 of the output surface of the cemented lens (71) satisfy: -0.85 <CR6 / SA6<-0.65 3mm≤SA6≤5mm.

4. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 3, characterized in that: The distance TD from the incident surface of the first lens (2) to the preset imaging surface of the system and the preset image surface size MTH of the system satisfy: 2.7 <TD / MTH<5 32mm≤TD≤40mm.

5. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 4, characterized in that: The curvature radius CR2 of the exit surface of the first lens (2) and the edge spacing ET12 between the first lens (2) and the second lens (3) satisfy: 4.7 <CR2 / ET12<28 0.35mm <ET12<1.5mm; The edge spacing ET23 between the second lens (3) and the third lens (4) and the edge spacing ET34 between the third lens (4) and the fourth lens (5) satisfy: 0.15 <ET23 / ET34<0.8 0.6mm <ET23<2mm。 6. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 5, characterized in that: The angle OG2 between the main ray of the edge field of view of the exit surface of the first lens (2) and the normal of the surface and the angle OG4 between the main ray of the edge field of view of the exit surface of the second lens (3) and the normal of the surface satisfy: 0.23 <OG2 / OG4<0.36 25° <OG4<30°; The angle IG5 between the incident principal ray of the edge field of view of the incident surface of the third lens (4) and the normal of the surface and the angle IG6 between the incident principal ray of the edge field of view of the exit surface of the fourth lens (5) and the normal of the surface satisfy: 1.75 <IG5 / IG6<2.81 16° <IG6<20°。 7. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 6, characterized in that: The center thickness CT2 of the second lens (3) and the center thickness CT3 of the third lens (4) are full Foot: 0.24 <CT2 / CT3<0.68 2.8mm <CT3<5mm; The center thickness CTS1 of the first cemented lens (71) and the center thickness CTS2 of the second cemented lens (72) satisfy: 0.57 <CTS1 / CTS2<1.6 2mm <CTS1<4mm。 8. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 7, characterized in that: The focal length f2 of the second lens (3) and the focal length f4 of the fourth lens (5) satisfy: -1.14 <f2 / f4<-0.72 14mm <f4<18mm; The focal length f5 of the fifth lens (6) and the system preset effective focal length f satisfy: 9.3 <f5 / f<24 40mm <f5<60mm。 9. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 8, characterized in that: The effective clear aperture SA14 of the incident surface of the sixth lens (8) and the distance T67 between the center of the exit surface of the cemented mirror (7) and the center of the incident surface of the sixth lens (8) on the optical axis of the optical path satisfy: 10 <SA14 / T67<80 6mm <SA14<8mm; The distance T2 between the center of the exit surface of the sixth lens (8) and the preset imaging surface of the system on the optical axis of the optical path satisfies: 3mm <T2<6mm。 10. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 1, characterized in that: It also includes an aperture stop (9), which is located between the fifth lens (6) and the cemented lens (7).

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