An ultra-wide angle large relative aperture amphibious optical system
By optimizing lens parameters and optical path design, the ultra-wide-angle, large relative aperture amphibious optical system solves the imaging difficulties in amphibious scenarios in existing technologies, achieving ultra-large field of view, large relative aperture imaging effect, and reducing manufacturing difficulty.
Patent Information
- Application Number
- CN202510792589.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2026-05-15
- Estimated Expiration
- 2045-06-13
AI Technical Summary
Existing optical systems struggle to achieve ultra-large field of view and large relative aperture in water-land reuse scenarios, and suffer from poor imaging quality and high manufacturing difficulty.
An ultra-wide-angle, large relative aperture amphibious optical system was designed, including a dome window, multiple lenses, and a detector. By optimizing lens parameters and optical path design, the system meets the requirements for amphibious use and reduces the number of lenses to lower the manufacturing difficulty.
It achieves ultra-wide field of view and large relative aperture imaging in amphibious scenarios, improving guidance accuracy and imaging quality, and reducing system size and manufacturing difficulty.
Smart Images
Figure CN120491291B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to optical systems, and more specifically to an ultra-wide-angle, large relative aperture amphibious optical system. Background Technology
[0002] With the continuous development of marine science and technology, autonomous underwater vehicles (AUVs) and other unmanned underwater platforms are playing an increasingly important role in marine environmental observation, marine resource development, and underwater engineering and operations due to their unmanned operation and information perception and feedback capabilities. To improve the quality and efficiency of underwater missions, AUVs require precise position and attitude information during their movement; therefore, underwater guidance technology has become an indispensable tool. Underwater optical guidance technology acquires target image information through underwater cameras and other optical sensors, and uses image processing and analysis techniques to provide the AUV with position, attitude, and other information. In close-range applications, compared to other guidance technologies such as underwater acoustic guidance, it boasts higher precision, larger information capacity, and stronger reliability, making it the optimal choice for close-range guidance.
[0003] On the other hand, monitoring targets above the water surface also plays a crucial role in underwater guidance in several ways. It helps to understand changes in the above-water working environment, providing underwater platforms with real-time dynamic information about the surrounding sea area. Through continuous tracking and analysis of the movement trajectory of surface targets, the future position and movement trend of the targets can be predicted, allowing for advance planning of underwater equipment routes. For example, using drones to photograph targets above the water surface can support the planning of underwater equipment routes.
[0004] To achieve the aforementioned underwater optical guidance and surface target monitoring, the transmission and presentation of target information by an optical system is indispensable. To save costs and improve the ease 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. While meeting the requirements for reuse in both water and land environments, to expand the range of underwater guidance and land target monitoring, the optical system needs to have an ultra-large field of view and a large relative aperture. Simultaneously, to improve the accuracy of underwater guidance and land target monitoring, the system also needs to have small differences in light spot size under different underwater fields of view and high imaging resolution in air. Furthermore, to better adapt to underwater and land-based platforms, the overall length and aperture of the optical system should be minimized. To reduce the system's manufacturing difficulty and cost, the number of lenses also needs to be reduced, and lens parameters strictly controlled. This presents significant difficulties and challenges to the design of the optical system. Summary of the Invention
[0005] The purpose of this invention is to solve the problems of existing optical systems having an ultra-wide field of view and a large relative aperture while meeting the requirements of amphibious use, as well as the technical problems of poor system guidance and imaging effects and high manufacturing difficulty, and to provide an ultra-wide-angle amphibious optical system with a large relative aperture.
[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0007] A unique amphibious optical system with an ultra-wide-angle and large relative aperture is characterized by:
[0008] It includes a spherical dome window, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a cemented mirror, a sixth lens, and a detector arranged sequentially along the optical path;
[0009] The first lens is a meniscus lens with negative optical power and a convex incident surface; the second lens is a meniscus lens with negative optical power and a convex incident surface; the third lens is a meniscus lens with positive optical power and a concave incident surface; the fourth lens is a biconvex lens with positive optical power; the fifth lens is a meniscus lens with positive optical power, wherein the incident surfaces are convex; the cemented lens has positive optical power and includes a first cemented lens and a second cemented lens arranged sequentially along the optical path, wherein the first cemented lens is a biconvex lens with positive optical power, the second cemented lens is a meniscus lens with negative optical power, and the incident surface of the second cemented lens is concave; the sixth lens is a meniscus lens with positive optical power and a convex incident surface.
[0010] The distance on the optical axis of the spherical dome window between the center of the exit surface and the center of the incident surface of the first lens is 6-17 mm; the distance on the optical axis of the exit surface of the first lens and the center of the incident surface of the second lens is 2.9-4.5 mm; the distance on the optical axis of the exit surface of the second lens and the center of the incident surface of the third lens is 5-6.5 mm; the distance on the optical axis of the optical axis of the exit surface of the third lens and the center of the incident surface of the fourth lens is 0.6-1.3 mm; the distance on the optical axis of the optical axis of the exit surface of the fourth lens and the center of the incident surface of the fifth lens is 0.3-1 mm; the distance on the optical axis of the optical axis of the exit surface of the fifth lens and the center of the incident surface of the cemented lens is 1.5-2.5 mm; and the distance on the optical axis of the optical axis of the optical axis of the exit surface of the cemented lens and the center of the incident surface of the sixth lens is 0.1-0.6 mm.
[0011] The dome window is a hemispherical dome, and the system preset aperture OA and the system preset effective focal length f satisfy the following:
[0012] 0.4 <OA / f<0.5
[0013] 1.1mm≤OA≤1.9mm.
[0014] Furthermore, the material of the dome window is H-K9L or N-BK7;
[0015] While ensuring pressure resistance, the system's field of view can be increased, and manufacturing costs can be reduced.
[0016] The inner diameter BS1 of the dome window and the thickness T1 of the dome window satisfy the following:
[0017] 2.4 <BS1 / T1<7.2
[0018] 38mm≤BS1≤45mm;
[0019] By satisfying the above relationships, the optomechanical properties of the window remain unchanged underwater, effectively improving the system's pressure resistance.
[0020] The inner diameter BS1 of the dome window and the effective light-transmitting diameter SA1 of the first lens incident surface satisfy the following:
[0021] 8mm <BS1-SA1<29mm
[0022] Satisfying the above relationships improves the compatibility between the dome window and the rear lens, and reduces the difficulty of installation;
[0023] The radius of curvature R2 of the exit surface of the dome window and the distance T12 between the center of the exit surface of the dome window and the center of the incident surface of the first lens on the optical axis of the optical path satisfy the following:
[0024] 1.11 <R2 / T12<4.58
[0025] Satisfying the above relationship can reduce the impact of refraction from the dome window on system performance, improve spherical aberration, coma, and astigmatism, and reduce the geometric differences between air and underwater light.
[0026] Furthermore, the radius of curvature CR1 of the incident surface of the first lens and the effective aperture SA1 of the incident surface of the first lens satisfy the following:
[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 radius of curvature CR2 of the exit surface of the first lens and the effective aperture SA2 of the exit surface of the first lens satisfy the following:
[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 be better matched with the detector;
[0033] The radius of curvature CR3 of the exit surface of the second lens and the effective aperture SA3 of the exit surface of the second lens satisfy the following:
[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 radius of curvature CR4 of the incident surface of the third lens and the effective aperture SA4 of the incident surface of the third lens satisfy the following:
[0038] -1.25 <CR4 / SA4<-0.75
[0039] 7mm≤SA4≤19mm;
[0040] Satisfying the above relationship can reduce the processing difficulty of the third lens and reduce the stray light effect from the exit surface of the first lens;
[0041] The radius of curvature CR5 of the exit surface of the fifth lens and the effective aperture SA5 of the exit surface of the fifth lens satisfy the following:
[0042] 0.8 <CR5 / SA5<1.3
[0043] 3.6mm≤SA5≤7.2mm;
[0044] Satisfying the above relationship can reduce the processing difficulty of the fifth lens and improve the system's light-gathering effect;
[0045] The radius of curvature CR6 of the exit surface of the cemented lens and the effective aperture SA6 of the exit surface of the cemented lens satisfy the following:
[0046] 0.65 <CR6 / SA6<0.85
[0047] 3mm≤SA6≤5mm.
[0048] Satisfying the above relationship can reduce the manufacturing difficulty and cost of cemented lens one and cemented lens two, and improve the illumination uniformity of the system image plane.
[0049] Furthermore, the distance TD from the incident surface of the first lens to the system's preset imaging surface satisfies the system's preset image plane size MTH:
[0050] 2.7 <TD / MTH<5
[0051] 32mm≤TD≤40mm;
[0052] By satisfying the above relationship, the image height can be effectively increased while ensuring a relatively small system length.
[0053] Furthermore, the radius of curvature CR2 of the exit surface of the first lens and the edge spacing ET12 between the first lens and the second lens satisfy the following:
[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 the following:
[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 principal ray emitted from the edge field of view of the first lens exiting surface and the normal to that surface, and the angle OG4 between the principal ray emitted from the edge field of view of the second lens exiting surface and the normal to that surface, satisfy the following:
[0062] 0.23 <OG2 / OG4<0.36
[0063] 25° <OG4<30°;
[0064] Satisfying the above relationship helps to prevent the light from deviating too much from the optical axis on the exit surface of the second lens, thus enhancing the system's control over off-axis aberrations.
[0065] The angle IG5 between the principal ray incident on the edge field of view of the third lens incident surface and the normal to that surface, and the angle IG6 between the principal ray incident on the edge field of view of the fourth lens exit surface and the normal to that surface, satisfy the following:
[0066] 1.75 <IG5 / IG6<2.81
[0067] 16° <IG6<20°。
[0068] By satisfying the above relationship, the degree to which the incident light rays deviate from the optical axis on the side of the third lens incident surface can be controlled within a reasonable range, reducing off-axis aberrations while improving the utilization rate of light energy.
[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 thickness difference between the second and third lenses, and at the same time facilitate the rational distribution of the thickness of each lens in the system.
[0072] The center thickness CTS1 of the cemented lens one and the center thickness CTS2 of the cemented lens two satisfy the following:
[0073] 0.57 <CTS1 / CTS2<1.6
[0074] 2mm <CTS1<4mm。
[0075] Satisfying the above relationship can effectively reduce the chromatic aberration of the system, making the thickness distribution of cemented lens one and cemented lens two more reasonable.
[0076] Furthermore, the focal length f2 of the second lens and the focal length f4 of the fourth lens satisfy the following:
[0077] -1.14 <f2 / f4<-0.72
[0078] 14mm <f4<18mm;
[0079] Satisfying the above relationship is beneficial for the rational allocation 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's preset effective focal length f satisfy the following:
[0081] 9.3 <f5 / f<24
[0082] 40mm <f5<60mm。
[0083] By satisfying the above relationship, the system's optical focal length is prevented from becoming too concentrated, while further improving the light-gathering effect.
[0084] Furthermore, the effective aperture SA14 of the incident surface of the sixth lens and the distance T67 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 satisfy the following:
[0085] 10 <SA14 / T67<80
[0086] 6mm <SA14<8mm;
[0087] Satisfying the above relationship effectively reduces the lens aperture and lowers the difficulty of system assembly and adjustment.
[0088] The distance T2 between the center of the exit surface of the sixth lens and the system's preset imaging surface on the optical axis of the optical path satisfies:
[0089] 3mm <T2<6mm。
[0090] Satisfying the above relationship reduces the difficulty of detector assembly and adjustment, and helps improve the system's performance.
[0091] Furthermore, it also includes an aperture stop, which is located between the fifth lens and the cemented lens.
[0092] This helps 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 beneficial effects of the present invention are:
[0094] This invention provides an ultra-wide-angle, large relative aperture amphibious optical system. By using a dome-shaped window as a protective window and employing the same parameters for both underwater and land applications, the system can be used both underwater and on land without additional adjustments. Through the rational design of the parameters of each lens, the overall size of the system is reduced, lowering the manufacturing difficulty. The system features an ultra-wide-angle field of view and a large relative aperture both underwater and on land, effectively improving signal presentation and processing during guidance, thus enhancing guidance accuracy. It also effectively improves signal presentation and processing during large-scale guidance. When imaging in air, it also features an ultra-large field of view and a large relative aperture with good image quality, effectively improving the effect of large-scale monitoring. Attached Figure Description
[0095] Figure 1 This is an optical path diagram of an embodiment of an ultra-wide-angle, large relative aperture amphibious optical system of the present invention;
[0096] Figure 2 This is a point diagram of an embodiment of the present invention with an object distance of 0.5m and the object medium being seawater;
[0097] Figure 3 This is a point diagram of an embodiment of the present invention with an object distance of 3m and the object medium being seawater;
[0098] Figure 4 This is a point diagram of an embodiment of the present invention with an object distance of 20m and the object medium being 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 medium on the object side 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 medium on the object side is air;
[0101] Figure 7 This is an MTF curve diagram of an embodiment of the present invention when the object distance is infinitely far and the medium on the object side is air.
[0102] The annotations in the attached figures are explained as follows:
[0103] 1-Spherical dome window, 2-First lens, 3-Second lens, 4-Third lens, 5-Fourth lens, 6-Fifth lens, 7-Cemented lens, 71-Cemented lens one, 72-Cemented lens two; 8-Sixth lens, 9-Aperture stop, 10-Detector. Detailed Implementation
[0104] The present invention will be further described below with reference to the accompanying drawings and exemplary embodiments.
[0105] Reference Figure 1 This invention discloses 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 arranged sequentially along the optical path. An aperture stop 9 is also provided between the fifth lens 6 and the cemented mirror 7. To meet the application requirements of amphibious use, based on the dome window 1 and a reverse telephoto structure, multiple structural configurations are implemented for both water and air working media, and for both blue light (430nm–470nm) and visible light (486nm–656nm) wavelengths. The field of view type is selected as angle, and the maximum aperture and length of the lens group are controlled to optimize the system's focusing spot underwater and imaging effect in air, resulting in the final design.
[0106] The technical specifications of this embodiment are shown in Table 1:
[0107] Table 1
[0108]
[0109] The first lens 2 is a meniscus lens with negative optical power and a convex incident surface; the second lens 3 is a meniscus lens with negative optical power and a convex incident surface; the third lens 4 is a meniscus lens with positive optical power and a concave incident surface; the fourth lens 5 is a biconvex lens with positive optical power; the fifth lens 6 is a meniscus lens with positive optical power and a convex incident surface; the cemented lens 7 has positive optical power and includes a first cemented lens 71 and a second cemented lens 72 arranged sequentially along the optical path. The first cemented lens 71 is a biconvex lens with positive optical power, and the second cemented lens 72 is a meniscus lens with negative optical power and a concave incident surface; the sixth lens 8 is a meniscus lens with positive optical power and a convex incident surface. After passing through the first lens 2, the second lens 3, and the third lens 4, the light beam diverges, and after passing through the remaining lenses, the light beam converges. This design effectively expands the field of view and reduces the system phase difference.
[0110] The detector 10 uses a Medtronic MV-GE300GC industrial camera with a pixel size of 3.45 micrometers, a resolution of 2048*1536, a diagonal size of 8.8mm, and an imaging height of 8.8mm in air. This achieves a high degree of matching between the detector and the camera target surface, and the underwater imaging height matching also reaches a high level. This helps to ensure the system's field of view and effectively improves the underwater spot detection accuracy and the imaging effect in air.
[0111] The dome window 1 is a hemispherical dome made of H-K9L or N-BK7 material. After installing the dome window 1, the system can operate at a water depth of up to 500m. The incident surface of the dome window 1 is uncoated, while the exit surface is coated with an anti-reflection film of 430nm-656nm. The incident and exit surfaces of the other lenses are also coated with an anti-reflection film of 430nm-656nm. The transmittance of the film layer is greater than 99%, which helps to enhance the system's energy utilization, improve the detector 10's response to underwater and air optical signals, and reduce the impact of stray light on the received signal.
[0112] The distance on the optical axis of the light path between the center of the exit surface of the dome window 1 and the center of the incident surface of the first lens 2 is 6-17 mm; the distance on the optical axis of the light path between the center of the exit surface of the first lens 2 and the center of the incident surface of the second lens 3 is 2.9-4.5 mm; the distance on the optical axis of the light path between the center of the exit surface of the second lens 3 and the center of the incident surface of the third lens 4 is 5-6.5 mm; the distance on the optical axis of the light path between the center of the exit surface of the third lens 4 and the center of the incident surface of the fourth lens 5 is 0.6-1.3 mm; the distance on the optical axis of the light path between the center of the exit surface of the fourth lens 5 and the center of the incident surface of the fifth lens 6 is 0.3-1 mm; the distance on the optical axis of the light path between the center of the exit surface of the fifth lens 6 and the center of the incident surface of the cemented lens 7 is 1.5-2.5 mm; and the distance on the optical axis of the light path between the center of the exit surface of the cemented lens 7 and the center of the incident surface of the sixth lens 8 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, "radius of curvature" refers to the radius of curvature of the optical surface of each lens, "thickness" refers to the thickness of the center of the lens or the thickness of the medium in front of and behind the lens, "material" refers to the material grade used for the lens, and "diameter" refers to the aperture diameter corresponding to each optical surface.
[0118] In the table above, the material of the system's object surface, i.e., the S0 surface, is seawater, which is suitable for underwater applications. If it is to be used on land, the material of the S0 surface needs to be changed to air. A dome window 1 is set behind the S0 surface to protect the lens. The outer and inner diameters of the dome are 60mm and 40mm respectively, which reduces the overall size of the system and makes the manufacturing process easier.
[0119] The system's focal length is controlled to be 2.88mm underwater and 4.01mm in air, with a relative aperture of 1 / 2.3, which expands the system's field of view, increases the system's light transmission, and enhances the light signal intensity.
[0120] With the dome window 1 included, the system has a maximum aperture of 60mm and an overall length of 64.3mm, effectively controlling the system size and facilitating installation in various scenarios. Without the dome window 1, the maximum aperture is only 23.3mm and the overall length is only 39.3mm, which facilitates lens assembly and improves adaptability to dome windows 1 of different specifications.
[0121] All lenses have spherical surfaces. By using a cemented lens 7 in conjunction with other single lenses, chromatic aberration correction is achieved while reducing the difficulty of assembly and engineering.
[0122] In this embodiment, each lens is designed with the following requirements:
[0123] (1) The system preset aperture OA and the system preset effective focal length f satisfy:
[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 transmission 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 the following:
[0128] 2.4 <BS1 / T1<7.2
[0129] 38mm≤BS1≤45mm.
[0130] (3) The inner diameter BS1 of the dome window 1 and the effective light-transmitting diameter SA1 of the incident surface of the first lens 2 satisfy the following:
[0131] 8mm <BS1-SA1<29mm。
[0132] (4) The radius of curvature R2 of the exit surface of the spherical window 1 and the distance T12 between the center of the exit surface of the spherical 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 radius of curvature 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 the following:
[0135] 0.75 <CR1 / SA1<1。
[0136] (6) The radius of curvature 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 the following:
[0137] 0.575 <CR2 / SA2<0.75
[0138] 10mm≤SA2≤22mm.
[0139] (7) The radius of curvature CR3 of the exit surface of the second lens 3 and the effective aperture SA3 of the exit surface of the second lens 3 satisfy the following:
[0140] 0.565 <CR3 / SA3<0.75
[0141] 8mm≤SA3≤20mm.
[0142] (8) The radius of curvature CR4 of the incident surface of the third lens 4 and the effective aperture SA4 of the incident surface of the third lens 4 satisfy the following:
[0143] -1.25 <CR4 / SA4<-0.75
[0144] 7mm≤SA4≤19mm.
[0145] (9) The radius of curvature CR5 of the exit surface of the fifth lens 6 and the effective aperture SA5 of the exit surface of the fifth lens 6 satisfy the following:
[0146] 0.8 <CR5 / SA5<1.3
[0147] 3.6mm≤SA5≤7.2mm.
[0148] (10) The radius of curvature CR6 of the exit surface of cemented lens-71 and the effective aperture SA6 of the exit surface of cemented lens-71 satisfy the following:
[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 system's preset imaging surface and the system's preset image surface size MTH satisfy the following:
[0152] 2.7 <TD / MTH<5
[0153] 32mm≤TD≤40mm.
[0154] (12) The radius of curvature 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:
[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 principal ray emitted from the edge field of view of the exit surface of the first lens 2 and the normal to that surface, and the angle OG4 between the principal ray emitted from the edge field of view of the exit surface of the second lens 3 and the normal to that surface, satisfy the following:
[0161] 0.23 <OG2 / OG4<0.36
[0162] 25° <OG4<30°。
[0163] (15) The angle IG5 between the principal ray incident on the edge field of view of the incident surface of the third lens 4 and the normal of that surface and the angle IG6 between the principal ray incident on the edge field of view of the exit surface of the fourth lens 5 and the normal of that surface satisfy the following:
[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 the following:
[0167] 0.24 <CT2 / CT3<0.68
[0168] 2.8mm <CT3<5mm。
[0169] (17) The center thickness CTS1 of cemented lens 1 71 and the center thickness CTS2 of cemented lens 2 72 satisfy the following:
[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 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 the following:
[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 system's preset imaging surface on the optical axis of the optical path satisfies:
[0182] 3mm <T2<6mm。
[0183] from Figures 2-4 It can be seen that when working underwater, the light spot formed by the system at object distances of 0.5m, 3mm and 20m is uniform in size and has a high consistency in shape. Moreover, the diameter of the focused light spot in each field of view is greater than 34.5um (10 times the pixel), which improves the accuracy of underwater guidance spot position information extraction and enhances the guidance effect.
[0184] from Figures 5-7 It can be seen that when working in the air, the system has a resolution better than 72 lp / mm at different field distances of 5m, 50m and infinity. The imaging resolution is good, which ensures that the system can obtain high image quality and meet the needs of land monitoring operations. It is especially suitable for UAV-borne applications.
[0185] The embodiments described above are merely illustrative of specific implementations of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. An ultra-wide-angle, large relative aperture amphibious optical system, characterized in that: It includes a spherical 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) arranged sequentially along the optical path; The first lens (2) is a meniscus lens with negative optical power and its incident surface is convex; the second lens (3) is a meniscus lens with negative optical power and its incident surface is convex; the third lens (4) is a meniscus lens with positive optical power and its incident surface is concave; the fourth lens (5) is a biconvex lens with positive optical power, and the fifth lens (6) is a meniscus lens with positive optical power, wherein the incident surface is convex; the cemented lens (7) has positive optical power and includes cemented lens one (71) and cemented lens two (72) arranged sequentially along the optical path, wherein cemented lens one (71) is a biconvex lens with positive optical power, and cemented lens two (72) is a meniscus lens with negative optical power, and the incident surface of cemented lens two (72) is concave; the sixth lens (8) is a meniscus lens with positive optical power and its incident surface is convex. The distance between the center of the exit surface of the dome window (1) and the center of the incident surface of the first lens (2) on the optical axis 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 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 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 is 6-17 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 is 0.6-1.3 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 mirror (7) on the optical axis 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 mirror (7) on the optical axis is 1.5-2.5 mm; the distance 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 is 0.1-0.6 mm; The dome window (1) is a hemispherical dome, and the system preset aperture OA and the system preset effective focal length f satisfy: 0.4 <OA / f<0.5; 1.1mm≤OA≤1.9mm; The material of the dome window (1) is H-K9L or N-BK7; The inner diameter BS1 of the dome window (1) and the thickness T1 of the dome window (1) satisfy the following: 2.4 <BS1 / T1<7.2; 38mm≤BS1≤45mm; The inner diameter BS1 of the dome window (1) and the effective light-transmitting diameter SA1 of the incident surface of the first lens (2) satisfy the following: 8mm <BS1-SA1<29mm; The radius of curvature R2 of the exit surface of the spherical window (1) and the distance T12 between the center of the exit surface of the spherical window (1) and the center of the incident surface of the first lens (2) on the optical axis of the optical path satisfy the following: 1.11 <R2 / T12<4.58。 2. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 1, characterized in that: The radius of curvature 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 the following: 0.75 <CR1 / SA1<1; The radius of curvature 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 the following: 0.575 <CR2 / SA2<0.75; 10mm≤SA2≤22mm; The radius of curvature CR3 of the exit surface of the second lens (3) and the effective aperture SA3 of the exit surface of the second lens (3) satisfy the following: 0.565 <CR3 / SA3<0.75; 8mm≤SA3≤20mm; The radius of curvature CR4 of the incident surface of the third lens (4) and the effective aperture SA4 of the incident surface of the third lens (4) satisfy the following: -1.25 <CR4 / SA4<-0.75; 7mm≤SA4≤19mm; The radius of curvature CR5 of the exit surface of the fifth lens (6) and the effective aperture SA5 of the exit surface of the fifth lens (6) satisfy the following: 0.8 <CR5 / SA5<1.3; 3.6mm≤SA5≤7.2mm; The radius of curvature CR6 of the exit surface of the cemented lens (71) satisfies the following condition: -0.85 <CR6 / SA6<-0.65; 3mm≤SA6≤5mm.
3. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 2, characterized in that: The distance TD from the incident surface of the first lens (2) to the system's preset imaging surface satisfies the following condition with respect to the system's preset image surface size MTH: 2.7 <TD / MTH<5; 32mm≤TD≤40mm.
4. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 3, characterized in that: The radius of curvature 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。 5. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 4, characterized in that: The angle OG2 between the principal ray emitted from the edge field of view of the first lens (2) and the normal of the surface, and the angle OG4 between the principal ray emitted from the edge field of view of the second lens (3) and the normal of the surface, satisfy the following: 0.23 <OG2 / OG4<0.36; 25° <OG4<30°; The angle IG5 between the principal ray incident on the edge field of view of the third lens (4) and the normal of the surface, and the angle IG6 between the principal ray incident on the edge field of view of the fourth lens (5) and the normal of the surface, satisfy the following: 1.75 <IG5 / IG6<2.81; 16° <IG6<20°。 6. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 5, characterized in that: The center thickness CT2 of the second lens (3) and the center thickness CT3 of the third lens (4) satisfy: 0.24 <CT2 / CT3<0.68; 2.8mm <CT3<5mm; The center thickness CTS1 of the cemented lens one (71) and the center thickness CTS2 of the cemented lens two (72) satisfy the following: 0.57 <CTS1 / CTS2<1.6; 2mm <CTS1<4mm。 7. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 6, characterized in that: The focal length f2 of the second lens (3) and the focal length f4 of the fourth lens (5) satisfy the following: -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。 8. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 7, characterized in that: The effective 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 the following: 10 <SA14 / T67<80; 6mm <SA14<8mm; The distance T2 between the center of the exit surface of the sixth lens (8) and the system preset imaging surface on the optical axis of the optical path satisfies: 3mm <T2<6mm。 9. The ultra-wide-angle, large relative aperture amphibious optical system according to claim 1, characterized in that: It also includes an aperture stop (9) located between the fifth lens (6) and the cemented lens (7).