Underwater observation lens

Abstract

The present application relates to a kind of underwater observation lens, by the spherical protective cover, first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, diaphragm, eighth lens, ninth lens, tenth lens, eleventh lens and twelfth lens are sequentially arranged from object side to image side along optical axis;Third lens and fourth lens form double cemented lens, eighth lens and ninth lens form double cemented lens, tenth lens and eleventh lens form double cemented lens, the rest of each lens is single lens.The present application overcomes the shortcomings that existing underwater imaging optical system is narrow in working wavelength range, large focal length zoom lens, cannot meet the needs of multiple, adopt the cooperation of spherical protective cover and twelve lenses, air gap, optical power, center thickness and the shape of each surface, radius of curvature and half diameter are optimized, its working wavelength range is wide, it is short focal length fixed focus lens, with the advantages of large aperture, large target surface, large field angle.

Description

Technical Field

[0001] This invention relates to an underwater observation lens, which is used in the field of underwater observation lens manufacturing. Background Technology

[0002] With technological breakthroughs in high-sensitivity, high-definition imaging devices and high-brightness lighting systems adapted for underwater photography, lenses have gradually expanded into the field of underwater exploration. However, the underwater environment differs from the atmospheric environment. Due to water refraction, objects observed underwater appear larger. Furthermore, light attenuation is enhanced in water, resulting in shorter observation distances. The water temperature is lower, and the presence of water pressure places higher demands on the lens's pressure resistance when used underwater. Therefore, compared to the atmospheric environment, designing lenses for underwater observation is more challenging. While existing underwater imaging optical systems exist (such as CN202211570338.1, a front-view underwater laser imaging optical system), they are narrow-range, long-focal-length zoom lenses (working band 525–535 nm, focal length 97 mm), which cannot meet the diverse needs of underwater observation. Therefore, providing an underwater observation lens with a wide working wavelength range, short focal length, fixed focus, and advantages such as large aperture, large target surface, and wide field of view has become an urgent priority. Summary of the Invention

[0003] To overcome the shortcomings of existing underwater imaging optical systems, which are narrow-range, large-focal-length zoom lenses that cannot meet the diverse needs of underwater observation, this invention provides an underwater observation lens that uses a spherical protective cover in conjunction with twelve lenses. The spherical protective cover, the air gaps of each lens, the optical power, the center thickness, and the shape, radius of curvature, and semi-diameter of each surface are optimized to achieve a wide working wavelength range. It is a short-focal-length fixed-focus lens with advantages such as a large aperture, a large target surface, and a wide field of view.

[0004] The technical solution of the present invention is as follows:

[0005] An underwater observation lens comprises a spherical protective cover, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an aperture, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, and a twelfth lens arranged sequentially along the optical axis from the object side to the image side; the third lens and the fourth lens form a cemented doublet, the eighth lens and the ninth lens form a cemented doublet, the tenth lens and the eleventh lens form a cemented doublet, and the remaining lenses are single lenses.

[0006] The air gap between the spherical protective cover and the first lens is 21.1 ± 0.2 mm.

[0007] The air gap between the first lens and the second lens is 8.320–10.006 mm.

[0008] The air gap between the second and third lenses is 5.395–5.526 mm.

[0009] The air gap between the fourth and fifth lenses is 0.103–0.169 mm.

[0010] The air gap between the fifth and sixth lenses is 0.131–0.559 mm.

[0011] The air gap between the sixth and seventh lenses is 7.533–8.622 mm.

[0012] The air gap between the seventh and eighth lenses is 5.384–5.529 mm.

[0013] The air gap between the ninth and tenth lenses is 0.099–0.117 mm.

[0014] The air gap between the eleventh and twelfth lenses is 0.099–0.102 mm;

[0015] The spherical protective cover is a negative power lens, with a convex first surface and a concave second surface.

[0016] The first lens is a negative power lens, with a convex first surface and a concave second surface.

[0017] The second lens is a negative power lens, with a convex first surface and a concave second surface.

[0018] The third lens is a negative power lens, with both the first and second surfaces being concave.

[0019] The fourth lens is a positive power lens, with both its first and second surfaces being convex.

[0020] The fifth lens is a positive power lens, with a flat first surface and a convex second surface.

[0021] The sixth lens is a positive power lens, with both its first and second surfaces being convex.

[0022] The seventh lens is a positive power lens, with both its first and second surfaces being convex.

[0023] The eighth lens is a negative power lens, with a convex first surface and a concave second surface.

[0024] The ninth lens is a positive power lens, with both its first and second surfaces being convex.

[0025] The tenth lens is a positive power lens, with both its first and second surfaces being convex.

[0026] The eleventh lens is a negative power lens, with a concave first surface and a convex second surface.

[0027] The twelfth lens is a negative power lens, with a concave first surface and a convex second surface;

[0028] The radius of curvature of the first surface of the first lens is 60.870–171.964 mm, and the radius of curvature of the second surface is 14.710–17.445 mm.

[0029] The radius of curvature of the first surface of the second lens is 46.158–63.6 mm, and the radius of curvature of the second surface is 15.322–15.37 mm.

[0030] The radius of curvature of the first surface of the third lens is -14.712 to -15.167 mm, and the radius of curvature of the second surface is 25.160 to 25.939 mm.

[0031] The radius of curvature of the first surface of the fourth lens is 25.160–25.939 mm, and the radius of curvature of the second surface is -25.194–-25.430 mm.

[0032] The first surface of the fifth lens is flat, and the radius of curvature of the second surface is -50.25 to -50.624 mm.

[0033] The radius of curvature of the first surface of the sixth lens is 92.061–98.022 mm, and the radius of curvature of the second surface is -97.75–104.640 mm.

[0034] The radius of curvature of the first surface of the seventh lens is 24.196–24.91 mm, and the radius of curvature of the second surface is -313.2–-540.435 mm.

[0035] The radius of curvature of the first surface of the eighth lens is 43.4–44.117 mm, and the radius of curvature of the second surface is 10.9–10.941 mm.

[0036] The radius of curvature of the first surface of the ninth lens is 10.9–10.941 mm, and the radius of curvature of the second surface is -57.850–-65.518 mm.

[0037] The tenth lens has a first surface radius of curvature of 17.814–18.387 mm and a second surface radius of curvature of -9.655–9.95 mm; the eleventh lens has a first surface radius of curvature of -9.655–9.95 mm and a second surface radius of curvature of -15.851–16.2 ​​mm; and the twelfth lens has a first surface radius of curvature of -21.982–22.95 mm and a second surface radius of curvature of -195.7–1085.342 mm.

[0038] The thickness of the spherical protective cover is 8±0.2mm.

[0039] The center thickness of the first lens is 1–4.97 mm.

[0040] The center thickness of the second lens is 6.8–8.003 mm.

[0041] The center thickness of the third lens is 4.256–4.31 mm.

[0042] The center thickness of the fourth lens is 6.95–6.989 mm.

[0043] The center thickness of the fifth lens is 5.65–5.805 mm.

[0044] The center thickness of the sixth lens is 6.73–8 mm.

[0045] The center thickness of the seventh lens is 5.2–5.423 mm.

[0046] The center thickness of the eighth lens is 1.3–1.368 mm.

[0047] The center thickness of the ninth lens is 5.556–6.6 mm.

[0048] The center thickness of the tenth lens is 7.155–7.21 mm.

[0049] The center thickness of the eleventh lens is 5.39–5.605 mm.

[0050] The center thickness of the twelfth lens is 3.052–7.155 mm.

[0051] This application's underwater observation lens employs a combination of a spherical protective cover and twelve lenses. The spherical protective cover, the air gaps between each lens, the optical power, the center thickness, and the shape, radius of curvature, and semi-diameter of each surface are optimally selected. It has a wide operating wavelength range, is a short focal length fixed-focus lens, and possesses advantages such as a large aperture, large target surface, and large field of view. This ensures stable, wide-field, clear imaging comparable to atmospheric conditions even in the low temperatures and high water pressure environments underwater. The design considers using a spherical cover (spherical protective cover) at the front end because a sphere can evenly distribute force when subjected to stress, eliminating stress concentration points. Within the spherical surface, the force is evenly distributed, resulting in greater pressure resistance per unit area. A water depth of 100 meters corresponds to 11 atmospheres of pressure. One atmosphere is 101.325 kPa, or 1.0332275 kg / cm². A 1mm thick dome glass in deep water can withstand approximately 3.66 kg / cm² of pressure. The dome glass in this design is 8-10mm thick, meaning it can theoretically withstand at least 28 atmospheres of pressure. This design can withstand water depths of at least 100 meters. Because the lens design also considers low-temperature optical compensation, all optical materials in the system meet the requirements for operating environments down to -30°C. Since this underwater observation lens is used underwater, where temperatures are generally above 0°C, low temperatures will not affect the product's normal function. The spherical protective cover is primarily used to protect the lens from water penetration. Compared to other shapes, the spherical cover has higher pressure resistance and deformation resistance. Furthermore, it ensures that the light beam emitted from the water, after passing through the cover, enters the rear optical system without deflection. It also balances the significant field curvature and astigmatism caused by the replacement of air with water in the spatial medium, thus achieving clear imaging. The underwater observation lens is installed in front of detector 15.

[0052] The underwater observation lens of this application has a focal length of 5.6mm±5%, an aperture of F0.9, a half-image height of up to 6.5mm, a total length of less than 128.061mm, a relative illumination of not less than 62%, can achieve day and night confocal focusing in the 380~905nm wavelength band, optical distortion can be reduced to <-66.84%, and it has a wide-angle observation field of 148°, which can ensure stable wide-field clear imaging comparable to atmospheric conditions in underwater low temperature and high water pressure environments.

[0053] The first surface of the first lens has a half-diameter of 22.440 ± 0.2 mm, and the second surface has a half-diameter of 13.170 ± 0.2 mm.

[0054] The first surface semi-diameter of the second lens is 12.286±0.2 mm, and the second surface semi-diameter is 8.609±0.2 mm.

[0055] The third lens has a first surface semi-diameter of 8.542 ± 0.2 mm and a second surface semi-diameter of 10.301 ± 0.2 mm.

[0056] The first surface semi-diameter of the fourth lens is 10.301±0.2 mm, and the second surface semi-diameter is 11±0.2 mm.

[0057] The first surface semi-diameter of the fifth lens is 11.748±0.2 mm, and the second surface semi-diameter is 12.3±0.2 mm.

[0058] The semi-diameter of the first surface of the sixth lens is 12.947±0.2 mm, and the semi-diameter of the second surface is 13.15±0.2 mm.

[0059] The first surface semi-diameter of the seventh lens is 12.35±0.2mm, and the second surface semi-diameter is 12.066±0.2mm.

[0060] The first surface semi-diameter of the eighth lens is 9.661±0.2 mm, and the second surface semi-diameter is 8.477±0.2 mm.

[0061] The first surface semi-diameter of the ninth lens is 8.477±0.2 mm, and the second surface semi-diameter is 8.311±0.2 mm.

[0062] The first surface semi-diameter of the tenth lens is 7.75±0.2mm, and the second surface semi-diameter is 7.765±0.2mm.

[0063] The semi-diameter of the first surface of the eleventh lens is 7.765±0.2 mm, and the semi-diameter of the second surface is 7.656±0.2 mm.

[0064] The first surface half-diameter of the twelfth lens is 7.308±0.2mm, and the second surface half-diameter is 7.16±0.2mm.

[0065] The optimized semi-diameter of each lens surface allows the lens as a whole to better fit the mechanical components, reduce light loss, and improve image quality.

[0066] The first lens is made of glass: 1.85 <n<2.10 25<Vd<35,

[0067] The second lens is made of glass: 1.45 <n<1.55 65<Vd<75,

[0068] The third lens is made of glass: 1.80 <n<2.10 25<Vd<35,

[0069] The fourth lens is made of glass: 1.50 <n<1.70 45<Vd<55,

[0070] The fifth lens is made of glass: 1.80 <n<2.10 25<Vd<35,

[0071] The sixth lens is made of glass: 1.80 <n<2.10 10<Vd<35,

[0072] The seventh lens is made of glass: 1.50 <n<1.60 55<Vd<65,

[0073] The eighth lens is made of glass: 1.80 <n<2.10 25<Vd<35,

[0074] The ninth lens is made of glass: 1.45 <n<1.65 65<Vd<75,

[0075] The tenth lens is made of glass: 1.45 <n<1.65 65<Vd<75,

[0076] The eleventh lens is made of glass: 1.45 <n<1.65 55<Vd<65,

[0077] The twelfth lens is made of glass: 1.80 <n<2.10 17<Vd<27;

[0078] Where n is the refractive index and Vd is the Abbe coefficient.

[0079] The optimal range of refractive index and Abbe coefficient represents a reasonable combination of optical power and dispersion correction in the entire optical system, which can optimize the imaging system to achieve good performance.

[0080] The spherical protective cover is made of glass.

[0081] The selected glass material protective cover has high transmittance, stronger corrosion resistance, and greater pressure resistance.

[0082] Compared with the prior art, this invention application has the following advantages:

[0083] The underwater observation lens of this application adopts a combination of a spherical protective cover and twelve lenses, and optimizes the spherical protective cover, the air gap of each lens, the optical power, the center thickness, and the shape, radius of curvature and semi-diameter of each surface. It has a wide working wavelength range, is a short focal length fixed-focus lens, and has the advantages of large aperture, large target surface and large field of view. Attached Figure Description

[0084] Figure 1 This is a structural diagram of the optical system of the underwater observation lens described in this invention;

[0085] Figure 2 This is the room temperature MTF chart of Embodiment 1 of the underwater observation lens described in this invention;

[0086] Figure 3 This is the -30℃ MTF chart of Embodiment 1 of the underwater observation lens described in this invention;

[0087] Figure 4 This is the 70℃ MTF chart of Embodiment 1 of the underwater observation lens described in this invention;

[0088] Figure 5 This is a dot diagram of Embodiment 1 of the underwater observation lens described in this invention;

[0089] Figure 6 This is a field curvature / distortion diagram of Embodiment 1 of the underwater observation lens described in this invention;

[0090] Figure 7 This is the illumination diagram of Embodiment 1 of the underwater observation lens described in this invention;

[0091] Figure 8 This is the room temperature MTF chart of Embodiment 2 of the underwater observation lens described in this invention;

[0092] Figure 9 This is the -30℃ MTF chart of Embodiment 2 of the underwater observation lens described in this invention;

[0093] Figure 10 This is the 70℃ MTF chart of Embodiment 2 of the underwater observation lens described in this invention;

[0094] Figure 11 This is a dot diagram of embodiment 2 of the underwater observation lens described in this invention;

[0095] Figure 12 This is the field curvature / distortion diagram of Embodiment 2 of the underwater observation lens described in this invention;

[0096] Figure 13 This is the illumination diagram of Embodiment 2 of the underwater observation lens described in this invention;

[0097] Figure 14 This is the room temperature MTF chart of embodiment 3 of the underwater observation lens described in this invention;

[0098] Figure 15 This is the -30℃ MTF chart of embodiment 3 of the underwater observation lens described in this invention;

[0099] Figure 16 This is the 70℃ MTF chart of embodiment 3 of the underwater observation lens described in this invention;

[0100] Figure 17 This is a dot diagram of embodiment 3 of the underwater observation lens described in this invention;

[0101] Figure 18 This is the field curvature / distortion diagram of embodiment 3 of the underwater observation lens described in this invention;

[0102] Figure 19 This is the illumination diagram of embodiment 3 of the underwater observation lens described in this invention.

[0103] Figure 20 This is the room temperature MTF chart of embodiment 4 of the underwater observation lens described in this invention;

[0104] Figure 21 This is the -30℃ MTF chart of embodiment 4 of the underwater observation lens described in this invention;

[0105] Figure 22 This is the 70℃ MTF chart of embodiment 4 of the underwater observation lens described in this invention;

[0106] Figure 23 This is a dot diagram of embodiment 4 of the underwater observation lens described in this invention;

[0107] Figure 24 This is the field curvature / distortion diagram of embodiment 4 of the underwater observation lens described in this invention;

[0108] Figure 25 This is the illumination diagram of embodiment 4 of the underwater observation lens described in this invention;

[0109] Figure 26 This is the room temperature MTF chart of embodiment 5 of the underwater observation lens described in this invention;

[0110] Figure 27 This is the -30℃ MTF chart of embodiment 5 of the underwater observation lens described in this invention;

[0111] Figure 28 This is the 70℃ MTF chart of embodiment 5 of the underwater observation lens described in this invention;

[0112] Figure 29 This is a dot diagram of embodiment 5 of the underwater observation lens described in this invention;

[0113] Figure 30 This is the field curvature / distortion diagram of embodiment 5 of the underwater observation lens described in this invention;

[0114] Figure 31 This is the illumination diagram of embodiment 5 of the underwater observation lens described in this invention.

[0115] Label Explanation:

[0116] 1. First lens, 2. Second lens, 3. Third lens, 4. Fourth lens, 5. Fifth lens, 6. Sixth lens, 7. Seventh lens, 8. Eighth lens, 9. Ninth lens, 10. Tenth lens, 11. Eleventh lens, 12. Twelfth lens, 13. Spherical protective cover, 14. Aperture, 15. Detector. Detailed Implementation

[0117] The following is in conjunction with the instruction manual appendix. Figure 1-31 The technical solution of the present invention will be described in detail below.

[0118] Example 1

[0119] As shown in Figures 1 and 2-7, the underwater observation lens of the present invention comprises a spherical protective cover 13, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture 14, an eighth lens 8, a ninth lens 9, a tenth lens 10, an eleventh lens 11, and a twelfth lens 12 arranged sequentially along the optical axis from the object side to the image side; the third lens 3 and the fourth lens 4 form a cemented doublet, the eighth lens 8 and the ninth lens 9 form a cemented doublet, the tenth lens 10 and the eleventh lens 11 form a cemented doublet, and the remaining lenses are single lenses.

[0120] The air gap between the spherical protective cover 13 and the first lens 1 is 21.1 mm.

[0121] The gap between the first lens 1 and the second lens 2 is 8.461 mm.

[0122] The gap between the second lens 2 and the third lens 3 is 5.526 mm.

[0123] The gap between the fourth lens 4 and the fifth lens 5 is 0.103 mm.

[0124] The gap between the fifth lens 5 and the sixth lens 6 is 0.131 mm.

[0125] The gap between the sixth lens 6 and the seventh lens 7 is 8.299 mm.

[0126] The gap between the seventh lens 7 and the eighth lens 8 is 5.384 mm.

[0127] The gap between the ninth lens 9 and the tenth lens 10 is 0.1 mm, and the gap between the eleventh lens 11 and the twelfth lens 12 is 0.1 mm.

[0128] The spherical protective cover 13 is a negative power lens, with a convex first surface and a concave second surface.

[0129] The first lens 1 is a negative power lens, with a convex first surface and a concave second surface.

[0130] The second lens 2 is a negative power lens, with a convex first surface and a concave second surface.

[0131] The third lens 3 is a negative power lens, with both its first and second surfaces being concave.

[0132] The fourth lens 4 is a positive power lens, with both its first and second surfaces being convex.

[0133] The fifth lens, 5, is a positive power lens; its first surface is flat, and its second surface is convex.

[0134] The sixth lens, 6, is a positive power lens; its first surface is convex, and its second surface is also convex.

[0135] The seventh lens 7 is a positive power lens, with both its first and second surfaces being convex.

[0136] The eighth lens, 8, is a negative power lens, with a convex first surface and a concave second surface.

[0137] The ninth lens 9 is a positive power lens, with both its first and second surfaces being convex.

[0138] The tenth lens 10 is a positive power lens, with both its first and second surfaces being convex.

[0139] The eleventh lens, 11, is a negative power lens, with a concave first surface and a convex second surface.

[0140] The twelfth lens 12 is a negative power lens, with a concave first surface and a convex second surface;

[0141] The first lens 1 has a first surface radius of curvature of 60.870 mm and a second surface radius of curvature of 14.710 mm; the second lens 2 has a first surface radius of curvature of 63.6 mm and a second surface radius of curvature of 15.37 mm; the third lens 3 has a first surface radius of curvature of -14.87 mm and a second surface radius of curvature of 25.43 mm; the fourth lens 4 has a first surface radius of curvature of 25.43 mm and a second surface radius of curvature of -25.430 mm; and the fifth lens 5 has a first surface that is flat and a second surface radius of curvature of -50.25 mm.

[0142] The radius of curvature of the first surface of the sixth lens 6 is 97.95 mm, and the radius of curvature of the second surface is -97.75 mm.

[0143] The radius of curvature of the first surface of the seventh lens 7 is 24.915 mm, and the radius of curvature of the second surface is -313.2 mm; the radius of curvature of the first surface of the eighth lens 8 is 43.4 mm, and the radius of curvature of the second surface is 10.9 mm; the radius of curvature of the first surface of the ninth lens 9 is 10.9 mm, and the radius of curvature of the second surface is -57.850 mm; the radius of curvature of the first surface of the tenth lens 10 is 18.150 mm, and the radius of curvature of the second surface is -9.95 mm; the radius of curvature of the first surface of the eleventh lens 11 is -9.95 mm, and the radius of curvature of the second surface is -16.2 mm; the radius of curvature of the first surface of the twelfth lens 12 is -22.5 mm, and the radius of curvature of the second surface is -195.7 mm.

[0144] The first surface of the first lens 1 has a half-diameter of 22.440 mm, and the second surface has a half-diameter of 13.170 mm.

[0145] The first surface semi-diameter of the second lens 2 is 12.286 mm, and the second surface semi-diameter is 8.609 mm.

[0146] The third lens 3 has a first surface semi-diameter of 8.542 mm and a second surface semi-diameter of 10.301 mm.

[0147] The first surface of the fourth lens 4 has a half-diameter of 10.301 mm, and the second surface has a half-diameter of 11 mm.

[0148] The first surface of the fifth lens 5 has a half-diameter of 11.748 mm, and the second surface has a half-diameter of 12.3 mm.

[0149] The first surface of the sixth lens 6 has a half-diameter of 12.947 mm, and the second surface has a half-diameter of 13.15 mm.

[0150] The first surface of the seventh lens 7 has a half-diameter of 12.35 mm, and the second surface has a half-diameter of 12.066 mm.

[0151] The first surface semi-diameter of the eighth lens 8 is 9.661 mm, and the second surface semi-diameter is 8.477 mm.

[0152] The first surface semi-diameter of the ninth lens 9 is 8.477 mm, and the second surface semi-diameter is 8.311 mm.

[0153] The tenth lens 10 has a first surface semi-diameter of 7.75 mm and a second surface semi-diameter of 7.765 mm.

[0154] The first surface of the eleventh lens 11 has a half-diameter of 7.765 mm, and the second surface has a half-diameter of 7.656 mm.

[0155] The first surface of the twelfth lens 12 has a semi-diameter of 7.308 mm, and the second surface has a semi-diameter of 7.16 mm; the thickness of the spherical protective cover 13 is 8 mm.

[0156] The center thickness of the first lens 1 is 4.87 mm.

[0157] The center thickness of the second lens 2 is 6.8 mm.

[0158] The center thickness of the third lens 3 is 4.31 mm.

[0159] The center thickness of the fourth lens 4 is 6.95mm.

[0160] The center thickness of the fifth lens 5 is 5.65mm.

[0161] The center thickness of the sixth lens 6 is 6.8 mm.

[0162] The center thickness of the seventh lens 7 is 5.2mm.

[0163] The center thickness of the eighth lens 8 is 1.3mm.

[0164] The center thickness of the ninth lens 9 is 6.6 mm.

[0165] The center thickness of the tenth lens 10 is 7.21 mm.

[0166] The center thickness of the eleventh lens 11 is 5.39 mm.

[0167] The center thickness of the twelfth lens 12 is 3.18 mm.

[0168] The first lens 1 is made of glass: 1.85 <n<2.10 25<Vd<35,

[0169] The second lens 2 is made of glass: 1.45 <n<1.55 65<Vd<75,

[0170] The third lens 3 is made of glass: 1.80 <n<2.10 25<Vd<35,

[0171] The fourth lens 4 is made of glass: 1.50 <n<1.70 45<Vd<55,

[0172] The fifth lens, 5, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0173] The sixth lens, 6, is made of glass: 1.80 <n<2.10 10<Vd<35,

[0174] The seventh lens 7 is made of glass: 1.50 <n<1.60 55<Vd<65,

[0175] The eighth lens, 8, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0176] The ninth lens, 9, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0177] The tenth lens, 10, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0178] The eleventh lens, 11, is made of glass: 1.45 <n<1.65 55<Vd<65,

[0179] The twelfth lens (12) is made of glass: 1.80 <n<2.10 17<Vd<27;

[0180] Where n is the refractive index and Vd is the Abbe coefficient.

[0181] The spherical protective cover 13 is made of glass.

[0182] The underwater observation lens of Example 1 is characterized by satisfying the following parameters:

[0183] Focal length: 5.667mm, F-number: 0.897, total optical length: 128.061mm, FOV: 148°, half-image height: 6.5mm, distortion <-66.84%, MTF across the entire field of view meets 125lp / mm>0.24, RMS radius <5.920um, relative illumination >62%.

[0184] Example 2

[0185] As shown in Figures 1 and 8-13, the underwater observation lens of the present invention comprises a spherical protective cover 13, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture 14, an eighth lens 8, a ninth lens 9, a tenth lens 10, an eleventh lens 11, and a twelfth lens 12 arranged sequentially along the optical axis from the object side to the image side; the third lens 3 and the fourth lens 4 form a cemented doublet, the eighth lens 8 and the ninth lens 9 form a cemented doublet, the tenth lens 10 and the eleventh lens 11 form a cemented doublet, and the remaining lenses are single lenses.

[0186] The air gap between the spherical protective cover 13 and the first lens 1 is 21.3 mm.

[0187] The gap between the first lens 1 and the second lens 2 is 10.006 mm.

[0188] The gap between the second lens 2 and the third lens 3 is 5.397 mm.

[0189] The gap between the fourth lens 4 and the fifth lens 5 is 0.169 mm.

[0190] The gap between the fifth lens 5 and the sixth lens 6 is 0.559 mm.

[0191] The gap between the sixth lens 6 and the seventh lens 7 is 8.622 mm.

[0192] The gap between the seventh lens 7 and the eighth lens 8 is 5.47 mm.

[0193] The gap between the ninth lens 9 and the tenth lens 10 is 0.1 mm, and the gap between the eleventh lens 11 and the twelfth lens 12 is 0.1 mm.

[0194] The spherical protective cover 13 is a negative power lens, with a convex first surface and a concave second surface.

[0195] The first lens 1 is a negative power lens, with a convex first surface and a concave second surface.

[0196] The second lens 2 is a negative power lens, with a convex first surface and a concave second surface.

[0197] The third lens 3 is a negative power lens, with both its first and second surfaces being concave.

[0198] The fourth lens 4 is a positive power lens, with both its first and second surfaces being convex.

[0199] The fifth lens, 5, is a positive power lens; its first surface is flat, and its second surface is convex.

[0200] The sixth lens, 6, is a positive power lens; its first surface is convex, and its second surface is also convex.

[0201] The seventh lens 7 is a positive power lens, with both its first and second surfaces being convex.

[0202] The eighth lens, 8, is a negative power lens, with a convex first surface and a concave second surface.

[0203] The ninth lens 9 is a positive power lens, with both its first and second surfaces being convex.

[0204] The tenth lens 10 is a positive power lens, with both its first and second surfaces being convex.

[0205] The eleventh lens, 11, is a negative power lens, with a concave first surface and a convex second surface.

[0206] The twelfth lens 12 is a negative power lens, with a concave first surface and a convex second surface;

[0207] The radius of curvature of the first surface of the first lens 1 is 171.964 mm, and the radius of curvature of the second surface is 17.445 mm.

[0208] The radius of curvature of the first surface of the second lens 2 is 53.665 mm, and the radius of curvature of the second surface is 15.322 mm.

[0209] The radius of curvature of the first surface of the third lens 3 is -14.870 mm, and the radius of curvature of the second surface is 25.430 mm.

[0210] The radius of curvature of the first surface of the fourth lens 4 is 25.430 mm, and the radius of curvature of the second surface is -25.194 mm.

[0211] The first surface of the fifth lens 5 is a plane, and the radius of curvature of the second surface is -50.624 mm.

[0212] The radius of curvature of the first surface of the sixth lens 6 is 98.022 mm, and the radius of curvature of the second surface is -97.853 mm.

[0213] The radius of curvature of the first surface of the seventh lens 7 is 24.196 mm, and the radius of curvature of the second surface is -540.435 mm.

[0214] The radius of curvature of the first surface of the eighth lens 8 is 44.103 mm, and the radius of curvature of the second surface is 10.935 mm.

[0215] The radius of curvature of the first surface of the ninth lens 9 is 10.935 mm, and the radius of curvature of the second surface is -65.518 mm.

[0216] The tenth lens 10 has a first surface radius of curvature of 17.814 mm and a second surface radius of curvature of -9.655 mm; the eleventh lens 11 has a first surface radius of curvature of -9.655 mm and a second surface radius of curvature of -15.851 mm; and the twelfth lens 12 has a first surface radius of curvature of -21.982 mm and a second surface radius of curvature of -530.739 mm.

[0217] The first surface of the first lens 1 has a half-diameter of 22.640 mm, and the second surface has a half-diameter of 12.97 mm.

[0218] The first surface semi-diameter of the second lens 2 is 12.486 mm, and the second surface semi-diameter is 8.409 mm.

[0219] The third lens 3 has a first surface semi-diameter of 8.742 mm and a second surface semi-diameter of 10.101 mm.

[0220] The first surface semi-diameter of the fourth lens 4 is 10.501 mm, and the second surface semi-diameter is 10.8 mm.

[0221] The first surface semi-diameter of the fifth lens 5 is 11.948 mm, and the second surface semi-diameter is 12.1 mm.

[0222] The first surface of the sixth lens 6 has a half-diameter of 13.147 mm, and the second surface has a half-diameter of 12.95 mm.

[0223] The first surface of the seventh lens 7 has a half-diameter of 12.55 mm, and the second surface has a half-diameter of 11.866 mm.

[0224] The first surface semi-diameter of the eighth lens 8 is 9.861 mm, and the second surface semi-diameter is 8.277 mm.

[0225] The first surface semi-diameter of the ninth lens 9 is 8.677 mm, and the second surface semi-diameter is 8.111 mm.

[0226] The tenth lens 10 has a first surface semi-diameter of 7.95 mm and a second surface semi-diameter of 7.565 mm.

[0227] The first surface of the eleventh lens 11 has a half-diameter of 7.965 mm, and the second surface has a half-diameter of 7.456 mm.

[0228] The first surface of the twelfth lens 12 has a half-diameter of 7.508 mm, and the second surface has a half-diameter of 6.96 mm.

[0229] The thickness of the spherical protective cover 13 is 8.2 mm.

[0230] The center thickness of the first lens 1 is 1 mm.

[0231] The center thickness of the second lens 2 is 8.003 mm.

[0232] The center thickness of the third lens 3 is 4.256 mm.

[0233] The center thickness of the fourth lens 4 is 6.989 mm.

[0234] The center thickness of the fifth lens 5 is 5.805 mm.

[0235] The center thickness of the sixth lens 6 is 8mm.

[0236] The center thickness of the seventh lens 7 is 5.230 mm.

[0237] The center thickness of the eighth lens 8 is 1.333 mm.

[0238] The center thickness of the ninth lens 9 is 5.556 mm.

[0239] The center thickness of the tenth lens 10 is 7.155 mm.

[0240] The center thickness of the eleventh lens 11 is 5.556 mm.

[0241] The center thickness of the twelfth lens 12 is 7.155 mm;

[0242] The first lens 1 is made of glass: 1.85 <n<2.10 25<Vd<35,

[0243] The second lens 2 is made of glass: 1.45 <n<1.55 65<Vd<75,

[0244] The third lens 3 is made of glass: 1.80 <n<2.10 25<Vd<35,

[0245] The fourth lens 4 is made of glass: 1.50 <n<1.70 45<Vd<55,

[0246] The fifth lens, 5, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0247] The sixth lens, 6, is made of glass: 1.80 <n<2.10 10<Vd<35,

[0248] The seventh lens 7 is made of glass: 1.50 <n<1.60 55<Vd<65,

[0249] The eighth lens, 8, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0250] The ninth lens, 9, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0251] The tenth lens, 10, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0252] The eleventh lens, 11, is made of glass: 1.45 <n<1.65 55<Vd<65,

[0253] The twelfth lens (12) is made of glass: 1.80 <n<2.10 17<Vd<27;

[0254] Where n is the refractive index and Vd is the Abbe coefficient.

[0255] The spherical protective cover 13 is made of glass.

[0256] Example 2: The underwater observation lens is characterized by satisfying the following parameters:

[0257] Focal length: 5.33mm, F number: 0.9, total optical length: 128.01mm, FOV: 148°, half image height: 5.5mm, distortion <-70.13%, MTF across the entire field of view meets 125lp / mm>0.3, RMS radius <3.899um, relative illumination >70%.

[0258] Example 3

[0259] As shown in Figures 1 and 14-19, the underwater observation lens of the present invention comprises a spherical protective cover 13, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture 14, an eighth lens 8, a ninth lens 9, a tenth lens 10, an eleventh lens 11, and a twelfth lens 12 arranged sequentially along the optical axis from the object side to the image side; the third lens 3 and the fourth lens 4 form a cemented doublet, the eighth lens 8 and the ninth lens 9 form a cemented doublet, the tenth lens 10 and the eleventh lens 11 form a cemented doublet, and the remaining lenses are single lenses.

[0260] The air gap between the spherical protective cover 13 and the first lens 1 is 20.9 mm.

[0261] The gap between the first lens 1 and the second lens 2 is 8.320 mm.

[0262] The gap between the second lens 2 and the third lens 3 is 5.395 mm.

[0263] The gap between the fourth lens 4 and the fifth lens 5 is 0.133 mm.

[0264] The gap between the fifth lens 5 and the sixth lens 6 is 0.285mm.

[0265] The gap between the sixth lens 6 and the seventh lens 7 is 7.533 mm.

[0266] The gap between the seventh lens 7 and the eighth lens 8 is 5.529 mm.

[0267] The gap between the ninth lens 9 and the tenth lens 10 is 0.117 mm, and the gap between the eleventh lens 11 and the twelfth lens 12 is 0.1 mm.

[0268] The spherical protective cover 13 is a negative power lens, with a convex first surface and a concave second surface.

[0269] The first lens 1 is a negative power lens, with a convex first surface and a concave second surface.

[0270] The second lens 2 is a negative power lens, with a convex first surface and a concave second surface.

[0271] The third lens 3 is a negative power lens, with both its first and second surfaces being concave.

[0272] The fourth lens 4 is a positive power lens, with both its first and second surfaces being convex.

[0273] The fifth lens, 5, is a positive power lens; its first surface is flat, and its second surface is convex.

[0274] The sixth lens, 6, is a positive power lens; its first surface is convex, and its second surface is also convex.

[0275] The seventh lens 7 is a positive power lens, with both its first and second surfaces being convex.

[0276] The eighth lens, 8, is a negative power lens, with a convex first surface and a concave second surface.

[0277] The ninth lens 9 is a positive power lens, with both its first and second surfaces being convex.

[0278] The tenth lens 10 is a positive power lens, with both its first and second surfaces being convex.

[0279] The eleventh lens, 11, is a negative power lens, with a concave first surface and a convex second surface.

[0280] The twelfth lens 12 is a negative power lens, with a concave first surface and a convex second surface;

[0281] The radius of curvature of the first surface of the first lens 1 is 113.327 mm, and the radius of curvature of the second surface is 16.999 mm.

[0282] The radius of curvature of the first surface of the second lens 2 is 46.158 mm, and the radius of curvature of the second surface is 15.327 mm.

[0283] The radius of curvature of the first surface of the third lens 3 is -14.870 mm, and the radius of curvature of the second surface is 25.430 mm.

[0284] The radius of curvature of the first surface of the fourth lens 4 is 25.430 mm, and the radius of curvature of the second surface is -25.223 mm.

[0285] The first surface of the fifth lens 5 is a plane, and the radius of curvature of the second surface is -50.347 mm.

[0286] The radius of curvature of the first surface of the sixth lens 6 is 92.061 mm, and the radius of curvature of the second surface is -104.640 mm.

[0287] The radius of curvature of the first surface of the seventh lens 7 is 24.301 mm, and the radius of curvature of the second surface is -493.527 mm.

[0288] The radius of curvature of the first surface of the eighth lens 8 is 44.117 mm, and the radius of curvature of the second surface is 10.941 mm.

[0289] The radius of curvature of the first surface of the ninth lens 9 is 10.941 mm, and the radius of curvature of the second surface is -60.342 mm.

[0290] The radius of curvature of the first surface of the tenth lens 10 is 18.387 mm, and the radius of curvature of the second surface is -9.752 mm.

[0291] The radius of curvature of the first surface of the eleventh lens 11 is -9.752 mm, and the radius of curvature of the second surface is -15.984 mm.

[0292] The radius of curvature of the first surface of the twelfth lens 12 is -22.014 mm, and the radius of curvature of the second surface is -1085.342 mm;

[0293] The first surface of the first lens 1 has a half-diameter of 22.240 mm, and the second surface has a half-diameter of 13.370 mm.

[0294] The first surface semi-diameter of the second lens 2 is 12.086 mm, and the second surface semi-diameter is 8.809 mm.

[0295] The third lens 3 has a first surface semi-diameter of 8.342 mm and a second surface semi-diameter of 10.501 mm.

[0296] The first surface semi-diameter of the fourth lens 4 is 10.101 mm, and the second surface semi-diameter is 11.2 mm.

[0297] The first surface of the fifth lens 5 has a half-diameter of 11.548 mm, and the second surface has a half-diameter of 12.5 mm.

[0298] The first surface of the sixth lens 6 has a half-diameter of 12.747 mm, and the second surface has a half-diameter of 13.35 mm.

[0299] The first surface of the seventh lens 7 has a half-diameter of 12.15 mm, and the second surface has a half-diameter of 12.266 mm.

[0300] The first surface semi-diameter of the eighth lens 8 is 9.461 mm, and the second surface semi-diameter is 8.677 mm.

[0301] The first surface semi-diameter of the ninth lens 9 is 8.277 mm, and the second surface semi-diameter is 8.511 mm.

[0302] The tenth lens 10 has a first surface semi-diameter of 7.55 mm and a second surface semi-diameter of 7.965 mm.

[0303] The first surface of the eleventh lens 11 has a half-diameter of 7.565 mm, and the second surface has a half-diameter of 7.856 mm.

[0304] The first surface of the twelfth lens 12 has a half-diameter of 7.108 mm, and the second surface has a half-diameter of 7.36 mm.

[0305] The thickness of the spherical protective cover 13 is 7.8 mm.

[0306] The center thickness of the first lens 1 is 1 mm.

[0307] The center thickness of the second lens 2 is 8mm.

[0308] The center thickness of the third lens 3 is 4.286 mm.

[0309] The center thickness of the fourth lens 4 is 6.976 mm.

[0310] The center thickness of the fifth lens 5 is 5.714 mm.

[0311] The center thickness of the sixth lens 6 is 8mm.

[0312] The center thickness of the seventh lens 7 is 5.423 mm.

[0313] The center thickness of the eighth lens 8 is 1.368 mm.

[0314] The center thickness of the ninth lens 9 is 5.935 mm.

[0315] The center thickness of the tenth lens 10 is 7.158 mm.

[0316] The center thickness of the eleventh lens 11 is 5.605 mm.

[0317] The center thickness of the twelfth lens 12 is 3.052 mm.

[0318] The first lens 1 is made of glass: 1.85 <n<2.10 25<Vd<35,

[0319] The second lens 2 is made of glass: 1.45 <n<1.55 65<Vd<75,

[0320] The third lens 3 is made of glass: 1.80 <n<2.10 25<Vd<35,

[0321] The fourth lens 4 is made of glass: 1.50 <n<1.70 45<Vd<55,

[0322] The fifth lens, 5, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0323] The sixth lens, 6, is made of glass: 1.80 <n<2.10 10<Vd<35,

[0324] The seventh lens 7 is made of glass: 1.50 <n<1.60 55<Vd<65,

[0325] The eighth lens, 8, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0326] The ninth lens, 9, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0327] The tenth lens, 10, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0328] The eleventh lens, 11, is made of glass: 1.45 <n<1.65 55<Vd<65,

[0329] The twelfth lens (12) is made of glass: 1.80 <n<2.10 17<Vd<27;

[0330] Where n is the refractive index and Vd is the Abbe coefficient.

[0331] The spherical protective cover 13 is made of glass.

[0332] Example 3: The underwater observation lens is characterized by satisfying the following parameters:

[0333] Focal length: 5.88mm, F-number: 0.917, total optical length: 125.653mm, FOV: 148°, half-image height: 6.28mm, distortion <-69.43%, MTF across the entire field of view meets 125lp / mm>0.39, RMS radius <3.094um, relative illumination >62%.

[0334] Example 4

[0335] As shown in Figures 1 and 20-25, the underwater observation lens of the present invention comprises a spherical protective cover 13, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture 14, an eighth lens 8, a ninth lens 9, a tenth lens 10, an eleventh lens 11, and a twelfth lens 12 arranged sequentially along the optical axis from the object side to the image side; the third lens 3 and the fourth lens 4 form a cemented doublet, the eighth lens 8 and the ninth lens 9 form a cemented doublet, the tenth lens 10 and the eleventh lens 11 form a cemented doublet, and the remaining lenses are single lenses.

[0336] The air gap between the spherical protective cover 13 and the first lens 1 is 21.522 mm.

[0337] The gap between the first lens 1 and the second lens 2 is 8.630 mm.

[0338] The gap between the second lens 2 and the third lens 3 is 5.636 mm.

[0339] The gap between the fourth lens 4 and the fifth lens 5 is 0.105mm.

[0340] The gap between the fifth lens 5 and the sixth lens 6 is 0.133 mm.

[0341] The gap between the sixth lens 6 and the seventh lens 7 is 8.465 mm.

[0342] The gap between the seventh lens 7 and the eighth lens 8 is 5.492 mm.

[0343] The gap between the ninth lens 9 and the tenth lens 10 is 0.102 mm, and the gap between the eleventh lens 11 and the twelfth lens 12 is 0.102 mm.

[0344] The spherical protective cover 13 is a negative power lens, with a convex first surface and a concave second surface.

[0345] The first lens 1 is a negative power lens, with a convex first surface and a concave second surface.

[0346] The second lens 2 is a negative power lens, with a convex first surface and a concave second surface.

[0347] The third lens 3 is a negative power lens, with both its first and second surfaces being concave.

[0348] The fourth lens 4 is a positive power lens, with both its first and second surfaces being convex.

[0349] The fifth lens, 5, is a positive power lens; its first surface is flat, and its second surface is convex.

[0350] The sixth lens, 6, is a positive power lens; its first surface is convex, and its second surface is also convex.

[0351] The seventh lens 7 is a positive power lens, with both its first and second surfaces being convex.

[0352] The eighth lens, 8, is a negative power lens, with a convex first surface and a concave second surface.

[0353] The ninth lens 9 is a positive power lens, with both its first and second surfaces being convex.

[0354] The tenth lens 10 is a positive power lens, with both its first and second surfaces being convex.

[0355] The eleventh lens, 11, is a negative power lens, with a concave first surface and a convex second surface.

[0356] The twelfth lens 12 is a negative power lens, with a concave first surface and a convex second surface;

[0357] The radius of curvature of the first surface of the first lens 1 is 62.087 mm, and the radius of curvature of the second surface is 15.004 mm.

[0358] The radius of curvature of the first surface of the second lens 2 is 64.872 mm, and the radius of curvature of the second surface is 15.677 mm.

[0359] The radius of curvature of the first surface of the third lens 3 is -15.167 mm, and the radius of curvature of the second surface is 25.939 mm.

[0360] The radius of curvature of the first surface of the fourth lens 4 is 25.939 mm, and the radius of curvature of the second surface is -25.939 mm.

[0361] The first surface of the fifth lens 5 is a plane, and the radius of curvature of the second surface is -51.255 mm.

[0362] The radius of curvature of the first surface of the sixth lens 6 is 99.705 mm, and the radius of curvature of the second surface is -99.705 mm.

[0363] The radius of curvature of the first surface of the seventh lens 7 is 25.413 mm, and the radius of curvature of the second surface is -319.464 mm.

[0364] The radius of curvature of the first surface of the eighth lens 8 is 44.268 mm, and the radius of curvature of the second surface is 11.118 mm.

[0365] The radius of curvature of the first surface of the ninth lens 9 is 11.118 mm, and the radius of curvature of the second surface is -59.007 mm.

[0366] The tenth lens 10 has a first surface radius of curvature of 18.513 mm and a second surface radius of curvature of -10.149 mm.

[0367] The radius of curvature of the first surface of the eleventh lens 11 is -10.149 mm, and the radius of curvature of the second surface is -16.524 mm.

[0368] The radius of curvature of the first surface of the twelfth lens 12 is -22.95 mm, and the radius of curvature of the second surface is -199.614 mm;

[0369] The first surface of the first lens 1 has a half-diameter of 22.889 mm, and the second surface has a half-diameter of 13.433 mm.

[0370] The first surface semi-diameter of the second lens 2 is 12.532 mm, and the second surface semi-diameter is 8.781 mm.

[0371] The third lens 3 has a first surface semi-diameter of 8.713 mm and a second surface semi-diameter of 10.507 mm.

[0372] The first surface semi-diameter of the fourth lens 4 is 10.507 mm, and the second surface semi-diameter is 11.22 mm.

[0373] The first surface of the fifth lens 5 has a half-diameter of 11.983 mm, and the second surface has a half-diameter of 12.546 mm.

[0374] The first surface semi-diameter of the sixth lens 6 is 13.206 mm, and the second surface semi-diameter is 13.413 mm.

[0375] The first surface of the seventh lens 7 has a half-diameter of 12.597 mm, and the second surface has a half-diameter of 12.307 mm.

[0376] The first surface semi-diameter of the eighth lens 8 is 9.855 mm, and the second surface semi-diameter is 8.646 mm.

[0377] The first surface semi-diameter of the ninth lens 9 is 8.646 mm, and the second surface semi-diameter is 8.478 mm.

[0378] The tenth lens 10 has a first surface semi-diameter of 7.905 mm and a second surface semi-diameter of 7.921 mm.

[0379] The first surface semi-diameter of the eleventh lens 11 is 7.921 mm, and the second surface semi-diameter is 7.809 mm.

[0380] The first surface half-diameter of the twelfth lens 12 is 7.454 mm, and the second surface half-diameter is 7.303 mm;

[0381] The thickness of the spherical protective cover 13 is 8.16 mm.

[0382] The center thickness of the first lens 1 is 4.97 mm.

[0383] The center thickness of the second lens 2 is 6.94 mm.

[0384] The center thickness of the third lens 3 is 4.40 mm.

[0385] The center thickness of the fourth lens 4 is 7.09 mm.

[0386] The center thickness of the fifth lens 5 is 5.76 mm.

[0387] The center thickness of the sixth lens 6 is 6.94 mm.

[0388] The center thickness of the seventh lens 7 is 5.30 mm.

[0389] The center thickness of the eighth lens 8 is 1.33 mm.

[0390] The center thickness of the ninth lens 9 is 6.73 mm.

[0391] The center thickness of the tenth lens 10 is 7.35 mm.

[0392] The center thickness of the eleventh lens 11 is 5.50 mm.

[0393] The center thickness of the twelfth lens 12 is 3.24 mm.

[0394] The first lens 1 is made of glass: 1.85 <n<2.10 25<Vd<35,

[0395] The second lens 2 is made of glass: 1.45 <n<1.55 65<Vd<75,

[0396] The third lens 3 is made of glass: 1.80 <n<2.10 25<Vd<35,

[0397] The fourth lens 4 is made of glass: 1.50 <n<1.70 45<Vd<55,

[0398] The fifth lens, 5, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0399] The sixth lens, 6, is made of glass: 1.80 <n<2.10 10<Vd<35,

[0400] The seventh lens 7 is made of glass: 1.50 <n<1.60 55<Vd<65,

[0401] The eighth lens, 8, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0402] The ninth lens, 9, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0403] The tenth lens, 10, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0404] The eleventh lens, 11, is made of glass: 1.45 <n<1.65 55<Vd<65,

[0405] The twelfth lens (12) is made of glass: 1.80 <n<2.10 17<Vd<27;

[0406] Where n is the refractive index and Vd is the Abbe coefficient.

[0407] The spherical protective cover 13 is made of glass.

[0408] The underwater observation lens of Example 4 is characterized by satisfying the following parameters:

[0409] Focal length: 5.781mm, F-number: 1.029, total optical length: 130.725mm, FOV: 148°, half-image height: 6.7mm, distortion <-66.84%, MTF across the entire field of view meets 125lp / mm>0.23, RMS radius <6.043um, relative illumination >62%.

[0410] Example 5

[0411] As shown in Figures 1, 26-31, the underwater observation lens of the present invention comprises a spherical protective cover 13, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an aperture 14, an eighth lens 8, a ninth lens 9, a tenth lens 10, an eleventh lens 11, and a twelfth lens 12 arranged sequentially along the optical axis from the object side to the image side; the third lens 3 and the fourth lens 4 form a cemented doublet, the eighth lens 8 and the ninth lens 9 form a cemented doublet, the tenth lens 10 and the eleventh lens 11 form a cemented doublet, and the remaining lenses are single lenses.

[0412] The air gap between the spherical protective cover 13 and the first lens 1 is 20.886 mm.

[0413] The gap between the first lens 1 and the second lens 2 is 8.371 mm.

[0414] The gap between the second lens 2 and the third lens 3 is 5.467 mm.

[0415] The gap between the fourth lens 4 and the fifth lens 5 is 0.102 mm.

[0416] The gap between the fifth lens 5 and the sixth lens 6 is 0.129 mm.

[0417] The gap between the sixth lens 6 and the seventh lens 7 is 8.211 mm.

[0418] The gap between the seventh lens 7 and the eighth lens 8 is 5.327 mm.

[0419] The gap between the ninth lens 9 and the tenth lens 10 is 0.099 mm.

[0420] The gap between the eleventh lens 11 and the twelfth lens 12 is 0.099 mm;

[0421] The spherical protective cover 13 is a negative power lens, with a convex first surface and a concave second surface.

[0422] The first lens 1 is a negative power lens, with a convex first surface and a concave second surface.

[0423] The second lens 2 is a negative power lens, with a convex first surface and a concave second surface.

[0424] The third lens 3 is a negative power lens, with both its first and second surfaces being concave.

[0425] The fourth lens 4 is a positive power lens, with both its first and second surfaces being convex.

[0426] The fifth lens, 5, is a positive power lens; its first surface is flat, and its second surface is convex.

[0427] The sixth lens, 6, is a positive power lens; its first surface is convex, and its second surface is also convex.

[0428] The seventh lens 7 is a positive power lens, with both its first and second surfaces being convex.

[0429] The eighth lens, 8, is a negative power lens, with a convex first surface and a concave second surface.

[0430] The ninth lens 9 is a positive power lens, with both its first and second surfaces being convex.

[0431] The tenth lens 10 is a positive power lens, with both its first and second surfaces being convex.

[0432] The eleventh lens, 11, is a negative power lens, with a concave first surface and a convex second surface.

[0433] The twelfth lens 12 is a negative power lens, with a concave first surface and a convex second surface;

[0434] The radius of curvature of the first surface of the first lens 1 is 60.225 mm, and the radius of curvature of the second surface is 14.554 mm.

[0435] The radius of curvature of the first surface of the second lens 2 is 62.926 mm, and the radius of curvature of the second surface is 15.207 mm.

[0436] The radius of curvature of the first surface of the third lens 3 is -14.712 mm, and the radius of curvature of the second surface is 25.160 mm.

[0437] The radius of curvature of the first surface of the fourth lens 4 is 25.160 mm, and the radius of curvature of the second surface is -25.160 mm.

[0438] The first surface of the fifth lens 5 is a plane, and the radius of curvature of the second surface is -49.717 mm.

[0439] The radius of curvature of the first surface of the sixth lens 6 is 96.714 mm, and the radius of curvature of the second surface is -96.713 mm.

[0440] The radius of curvature of the first surface of the seventh lens 7 is 24.651 mm, and the radius of curvature of the second surface is -309.881 mm.

[0441] The radius of curvature of the first surface of the eighth lens 8 is 42.94 mm, and the radius of curvature of the second surface is 10.784 mm.

[0442] The radius of curvature of the first surface of the ninth lens 9 is 10.784 mm, and the radius of curvature of the second surface is -57.237 mm.

[0443] The tenth lens 10 has a first surface radius of curvature of 17.958 mm and a second surface radius of curvature of -9.845 mm; the eleventh lens 11 has a first surface radius of curvature of -9.845 mm and a second surface radius of curvature of -16.028 mm; and the twelfth lens 12 has a first surface radius of curvature of -22.262 mm and a second surface radius of curvature of -193.626 mm.

[0444] The first surface of the first lens 1 has a half-diameter of 22.202 mm, and the second surface has a half-diameter of 13.030 mm.

[0445] The first surface semi-diameter of the second lens 2 is 12.156 mm, and the second surface semi-diameter is 8.517 mm.

[0446] The third lens 3 has a first surface half-diameter of 8.452 mm and a second surface half-diameter of 10.192 mm.

[0447] The first surface semi-diameter of the fourth lens 4 is 10.192 mm, and the second surface semi-diameter is 10.883 mm.

[0448] The first surface of the fifth lens 5 has a half-diameter of 11.623 mm, and the second surface has a half-diameter of 12.17 mm.

[0449] The first surface of the sixth lens 6 has a half-diameter of 12.809 mm, and the second surface has a half-diameter of 13.010 mm.

[0450] The first surface of the seventh lens 7 has a half-diameter of 12.22 mm, and the second surface has a half-diameter of 11.938 mm.

[0451] The first surface semi-diameter of the eighth lens 8 is 9.559 mm, and the second surface semi-diameter is 8.387 mm.

[0452] The first surface semi-diameter of the ninth lens 9 is 8.387 mm, and the second surface semi-diameter is 8.223 mm.

[0453] The tenth lens 10 has a first surface semi-diameter of 7.668 mm and a second surface semi-diameter of 7.683 mm.

[0454] The first surface of the eleventh lens 11 has a half-diameter of 7.683 mm, and the second surface has a half-diameter of 7.575 mm.

[0455] The first surface half-diameter of the twelfth lens 12 is 7.23 mm, and the second surface half-diameter is 7.084 mm;

[0456] The thickness of the spherical protective cover 13 is 7.92 mm.

[0457] The center thickness of the first lens 1 is 4.82 mm.

[0458] The center thickness of the second lens 2 is 6.73 mm.

[0459] The center thickness of the third lens 3 is 4.26 mm.

[0460] The center thickness of the fourth lens 4 is 6.88 mm.

[0461] The center thickness of the fifth lens 5 is 5.59 mm.

[0462] The center thickness of the sixth lens 6 is 6.73 mm.

[0463] The center thickness of the seventh lens 7 is 5.14 mm.

[0464] The center thickness of the eighth lens 8 is 1.29 mm.

[0465] The center thickness of the ninth lens 9 is 6.53 mm.

[0466] The center thickness of the tenth lens 10 is 7.13 mm.

[0467] The center thickness of the eleventh lens 11 is 5.33 mm.

[0468] The center thickness of the twelfth lens 12 is 3.15 mm.

[0469] The first lens 1 is made of glass: 1.85 <n<2.10 25<Vd<35,

[0470] The second lens 2 is made of glass: 1.45 <n<1.55 65<Vd<75,

[0471] The third lens 3 is made of glass: 1.80 <n<2.10 25<Vd<35,

[0472] The fourth lens 4 is made of glass: 1.50 <n<1.70 45<Vd<55,

[0473] The fifth lens, 5, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0474] The sixth lens, 6, is made of glass: 1.80 <n<2.10 10<Vd<35,

[0475] The seventh lens 7 is made of glass: 1.50 <n<1.60 55<Vd<65,

[0476] The eighth lens, 8, is made of glass: 1.80 <n<2.10 25<Vd<35,

[0477] The ninth lens, 9, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0478] The tenth lens, 10, is made of glass: 1.45 <n<1.65 65<Vd<75,

[0479] The eleventh lens, 11, is made of glass: 1.45 <n<1.65 55<Vd<65,

[0480] The twelfth lens (12) is made of glass: 1.80 <n<2.10 17<Vd<27;

[0481] Where n is the refractive index and Vd is the Abbe coefficient.

[0482] The spherical protective cover 13 is made of glass.

[0483] The underwater observation lens of Example 5 is characterized by satisfying the following parameters:

[0484] Focal length: 5.608mm, F-number: 1.029, total optical length: 126.803mm, FOV: 148°, half-image height: 6.5mm, distortion <-66.84%, full-field MTF meets 125lp / mm>0.24, RMS radius <5.861um, relative illumination >62%.

[0485] The underwater observation lens described in this invention is not limited to the above embodiments. Any improvements or substitutions based on the principles of this invention should be within the protection scope of this invention.

Claims

1. An underwater observation lens, characterized in that: It consists of a spherical protective cover (13), a first lens (1), a second lens (2), a third lens (3), a fourth lens (4), a fifth lens (5), a sixth lens (6), a seventh lens (7), an aperture (14), an eighth lens (8), a ninth lens (9), a tenth lens (10), an eleventh lens (11), and a twelfth lens (12) arranged sequentially along the optical axis from the object side to the image side; the third lens (3) and the fourth lens (4) form a cemented doublet, the eighth lens (8) and the ninth lens (9) form a cemented doublet, the tenth lens (10) and the eleventh lens (11) form a cemented doublet, and the remaining lenses are single lenses; The air gap between the spherical protective cover (13) and the first lens (1) is 21.1 ± 0.2 mm. The air gap between the first lens (1) and the second lens (2) is 8.320–10.006 mm. The air gap between the second lens (2) and the third lens (3) is 5.395–5.526 mm. The air gap between the fourth lens (4) and the fifth lens (5) is 0.103–0.169 mm. The air gap between the fifth lens (5) and the sixth lens (6) is 0.131–0.559 mm. The air gap between the sixth lens (6) and the seventh lens (7) is 7.533–8.622 mm. The air gap between the seventh lens (7) and the eighth lens (8) is 5.384–5.529 mm. The air gap between the ninth lens (9) and the tenth lens (10) is 0.099–0.117 mm. The air gap between the eleventh lens (11) and the twelfth lens (12) is 0.099 to 0.102 mm; The spherical protective cover (13) is a negative power lens, with a convex first surface and a concave second surface. The first lens (1) is a negative power lens, with a convex first surface and a concave second surface. The second lens (2) is a negative power lens, with a convex first surface and a concave second surface. The third lens (3) is a negative power lens, with its first surface being concave and its second surface being concave. The fourth lens (4) is a positive power lens, with a convex first surface and a convex second surface. The fifth lens (5) is a positive power lens, with a flat first surface and a convex second surface. The sixth lens (6) is a positive power lens, with a convex first surface and a convex second surface. The seventh lens (7) is a positive power lens, with a convex first surface and a convex second surface. The eighth lens (8) is a negative power lens, with a convex first surface and a concave second surface. The ninth lens (9) is a positive power lens, with a convex first surface and a convex second surface. The tenth lens (10) is a positive power lens, with a convex first surface and a convex second surface. The eleventh lens (11) is a negative power lens, with a concave first surface and a convex second surface. The twelfth lens (12) is a negative power lens, with the first surface being concave and the second surface being convex. The radius of curvature of the first surface of the first lens (1) is 60.870–171.964 mm, and the radius of curvature of the second surface is 14.710–17.445 mm. The radius of curvature of the first surface of the second lens (2) is 46.158–63.6 mm, and the radius of curvature of the second surface is 15.322–15.37 mm. The radius of curvature of the first surface of the third lens (3) is -14.712 to -15.167 mm, and the radius of curvature of the second surface is 25.160 to 25.939 mm. The radius of curvature of the first surface of the fourth lens (4) is 25.160~25.939 mm, and the radius of curvature of the second surface is -25.194~-25.430 mm. The first surface of the fifth lens (5) is a plane, and the radius of curvature of the second surface is -50.25 to -50.624 mm. The radius of curvature of the first surface of the sixth lens (6) is 92.061–98.022 mm, and the radius of curvature of the second surface is -97.75–104.640 mm. The radius of curvature of the first surface of the seventh lens (7) is 24.196–24.91 mm, and the radius of curvature of the second surface is -313.2–-540.435 mm. The radius of curvature of the first surface of the eighth lens (8) is 43.4–44.117 mm, and the radius of curvature of the second surface is 10.9–10.941 mm. The radius of curvature of the first surface of the ninth lens (9) is 10.9–10.941 mm, and the radius of curvature of the second surface is -57.850–-65.518 mm. The radius of curvature of the first surface of the tenth lens (10) is 17.814–18.387 mm, and the radius of curvature of the second surface is -9.655–-9.95 mm. The radius of curvature of the first surface of the eleventh lens (11) is -9.655 to -9.95 mm, and the radius of curvature of the second surface is -15.851 to -16.2 mm. The radius of curvature of the first surface of the twelfth lens (12) is -21.982~-22.95mm, and the radius of curvature of the second surface is -195.7~-1085.342mm; The thickness of the spherical protective cover (13) is 8±0.2mm. The center thickness of the first lens (1) is 1~4.97mm. The center thickness of the second lens (2) is 6.8–8.003 mm. The center thickness of the third lens (3) is 4.256–4.31 mm. The center thickness of the fourth lens (4) is 6.95–6.989 mm. The center thickness of the fifth lens (5) is 5.65–5.805 mm. The center thickness of the sixth lens (6) is 6.73~8mm. The center thickness of the seventh lens (7) is 5.2–5.423 mm. The center thickness of the eighth lens (8) is 1.3–1.368 mm. The center thickness of the ninth lens (9) is 5.556–6.6 mm. The center thickness of the tenth lens (10) is 7.155–7.21 mm. The center thickness of the eleventh lens (11) is 5.39–5.605 mm. The center thickness of the twelfth lens (12) is 3.052–7.155 mm; The underwater observation lens has a short focal length of 5.6mm±5%, a large aperture, and a wide-angle field of view of 148°.

2. The underwater observation lens according to claim 1, characterized in that: The first surface of the first lens (1) has a half-diameter of 22.440±0.2mm, and the second surface has a half-diameter of 13.170±0.2mm. The first surface semi-diameter of the second lens (2) is 12.286±0.2mm, and the second surface semi-diameter is 8.609±0.2mm. The first surface semi-diameter of the third lens (3) is 8.542±0.2mm, and the second surface semi-diameter is 10.301±0.2mm. The first surface semi-diameter of the fourth lens (4) is 10.301±0.2mm, and the second surface semi-diameter is 11±0.2mm. The first surface semi-diameter of the fifth lens (5) is 11.748±0.2mm, and the second surface semi-diameter is 12.3±0.2mm. The first surface semi-diameter of the sixth lens (6) is 12.947±0.2mm, and the second surface semi-diameter is 13.15±0.2mm. The first surface semi-diameter of the seventh lens (7) is 12.35±0.2mm, and the second surface semi-diameter is 12.066±0.2mm. The first surface semi-diameter of the eighth lens (8) is 9.661±0.2mm, and the second surface semi-diameter is 8.477±0.2mm. The first surface semi-diameter of the ninth lens (9) is 8.477±0.2mm, and the second surface semi-diameter is 8.311±0.2mm. The first surface semi-diameter of the tenth lens (10) is 7.75±0.2mm, and the second surface semi-diameter is 7.765±0.2mm. The first surface semi-diameter of the eleventh lens (11) is 7.765±0.2mm, and the second surface semi-diameter is 7.656±0.2mm. The first surface half-diameter of the twelfth lens (12) is 7.308±0.2mm, and the second surface half-diameter is 7.16±0.2mm.

3. The underwater observation lens according to claim 1, characterized in that: The first lens (1) is made of glass: 1.85 <n<2.10 25<Vd<35, The second lens (2) is made of glass: 1.45 <n<1.55 65<Vd<75, The third lens (3) is made of glass: 1.80 <n<2.10 25<Vd<35, The fourth lens (4) is made of glass: 1.50 <n<1.70 45<Vd<55, The fifth lens (5) is made of glass: 1.80 <n<2.10 25<Vd<35, The sixth lens (6) is made of glass: 1.80 <n<2.10 10<Vd<35, The seventh lens (7) is made of glass: 1.50 <n<1.60 55<Vd<65, The eighth lens (8) is made of glass: 1.80 <n<2.10 25<Vd<35, The ninth lens (9) is made of glass: 1.45 <n<1.65 65<Vd<75, The tenth lens (10) is made of glass: 1.45 <n<1.65 65<Vd<75, The eleventh lens (11) is made of glass: 1.45 <n<1.65 55<Vd<65, The twelfth lens (12) is made of glass: 1.80 <n<2.10 17<Vd<27; Where n is the refractive index and Vd is the Abbe coefficient.

4. The underwater observation lens according to claim 1, characterized in that: The spherical protective cover (13) is made of glass.

Images