A fisheye lens

Abstract

The present invention relates to the field of lenses, and particularly to a fish-eye lens. A fish-eye lens includes a front lens group, a diaphragm, and a rear lens group arranged in sequence along the light incident direction. The ratio of the focal length f of the fish-eye lens to the focal length f1 of the front lens group is: -4.2 < f / f1 < -3.6, and the ratio of the focal length f of the fish-eye lens to the focal length f2 of the rear lens group is: 3.4 < f / f2 < 5.5. The F-thera distortion of the fish-eye lens of the present invention can reach +10%, the field of view angle: >190°, the application spectral range is: 400 - 950 nm, 10 pixels / ° at the center, >19.5 pixels / ° at the edge, and the applicable pixel size of the sensor: >1.5 um, and it can be applicable to environments with high requirements for edge images.

Description

Technical Field

[0001] The invention relates to the field of lenses, in particular to a fisheye lens. Background Art

[0002] Fisheye lens is a short focal length ultra-wide-angle lens with an angle close to or even exceeding 180°. It is called fisheye lens because its structure is similar to the eyes of fish. Fisheye lens has large optical distortion and severe edge image deformation and compression, and it is necessary to use algorithms to decompress and restore the image for easy observation. The fisheye lens based on bionics can "compress and deform" the object space by introducing barrel distortion, thereby obtaining ultra-wide-angle imaging with a viewing angle of 180 to 270 degrees without affecting the resolution.

[0003] Conventional optical system imaging follows the Gaussian optical principle. When the object is at a finite distance, y'=βy; when the object is at an infinite distance, y'=f*tan(ω). In the formula: y' is the ideal image height; β is the lateral magnification; y is the actual image height; f is the object focal length; ω is the object half-viewing angle, which is greater than 90 degrees. Fisheye lens is an ultra-wide-angle objective lens, which is widely used in imaging systems with a large field of view. It has the characteristics of short focal length and large field of view. Its field of view angle is about 180 degrees, and even 270 degrees. Therefore, fisheye lens imaging must adopt a "non-similar" imaging principle, that is, introducing a large amount of barrel distortion to image the object range that cannot be imaged by Gaussian optics through deformation and compression.

[0004] Different barrel distortions correspond to different correction models, which can be expressed by the following imaging formula:

[0005] For equidistant projection imaging, the field of view angle is proportional to the image height: y' = f*ω;

[0006] Orthogonal projection imaging has different radial and tangential magnifications when imaging spherical objects: y' = f*sin(ω);

[0007] For equal solid angle projection imaging, the process of inverse trigonometric function calculation will affect the accuracy and reduce the real-time performance: y'=2f*sin(ω / 2);

[0008] Stereoscopic projection imaging has the same radial and tangential magnification when imaging spherical objects: y' = 2f*tan(ω / 2);

[0009] The decompression algorithms for fisheye images on the market basically adopt the equidistant projection method, y’ = f * ω, and the distortion is f - thera. According to the distortion formula, f - thera dist = (y - y’) / y’, where y is the actual image height and y’ is the theoretical image height. It can be seen that the smaller the actual image height, the smaller the F - thera distortion, the more severe the compression of the image edge, and the more severe the degradation of the image quality at the edge after image restoration. On the contrary, the larger the actual image height, the larger the F - thera distortion. After image restoration, the image quality at the edge is better.

[0010] The F - thera distortion of most fisheye lenses on the market is about - 20% to - 5%. For example, Figure 2 the F - thera of the conventional fisheye lens shown is only about - 6%. The F - thera of a small number of fisheye lenses is within + 2%. Such fisheye lenses have no problem in most scenarios, but they are insufficient in situations where high requirements are placed on the edge image, such as video conferencing. Moreover, for conventional fisheye lenses, there are only 15 pixels / ° at the center and 10 pixels / ° at the edge.

[0011] For example, Figure 1 、 3 It can be seen that the first lens of the conventional fisheye lens and the first surface of the second lens bear most of the distortion aberrations. The R (radius of curvature) value of the first surface of the second lens is relatively large. Due to the need to balance other aberrations, the incident angle of light between the first lens and the second lens is small, and the contribution to the correction of F - thera is limited. To ensure the resolution of the lens, it is necessary to sacrifice the F - thera distortion so that the light at the edge is more concentrated. Summary of the Invention

[0012] The purpose of the present invention is to provide a fisheye lens. The F - thera distortion of this fisheye lens can reach + 10%, the field of view angle: > 190°, the application spectral range is: 400 - 950 nm, 10 pixels / ° at the center, > 19.5 pixels / ° at the edge, and the applicable pixel size of the sensor: > 1.5um. It can be applied to environments with high requirements for edge images.

[0013] The present invention is realized through the following technical solutions: A fisheye lens, characterized in that it includes a front lens group, a diaphragm, and a rear lens group arranged in sequence along the light incident direction. The ratio of the focal length f of the fisheye lens to the focal length f1 of the front lens group is: - 4.2 < f / f1 < - 3.6, and the ratio of the focal length f of the fisheye lens to the focal length f2 of the rear lens group is: 3.4 < f / f2 < 5.5.

[0014] Preferably, the focal length f1 of the front lens group is: -4mm to -6mm, and the front lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence along the incident direction of light;

[0015] The air gap between the first lens and the second lens is: 2mm-3mm;

[0016] The air gap between the second lens and the third lens is: 2mm~3mm;

[0017] The air gap between the third lens and the fourth lens is: 1.5mm~2.5mm;

[0018] The fourth lens and the fifth lens form a closely bonded lens group;

[0019] The air gap between the fifth lens and the sixth lens is: 0.1mm-0.3mm;

[0020] The air gap between the sixth lens and the aperture is: 0.2mm~0.5mm;

[0021] The focal length f2 of the rear lens group is 5 mm to 8 mm, and the rear lens group includes a seventh lens, an eighth lens, a ninth lens, and a tenth lens arranged in sequence along the incident direction of the light;

[0022] The air gap between the aperture and the seventh lens is: 0-0.5 mm;

[0023] The seventh lens and the eighth lens form a closely bonded lens group;

[0024] The air gap between the eighth lens and the ninth lens is 1 mm to 1.5 mm;

[0025] The ninth lens and the tenth lens form a closely bonded lens group;

[0026] The lenses also meet the following conditions:

[0027] 1.75 <N1<1.85,40<V1<55,2<D1<3,15<1R1<20,7<1R2<8.5;

[0028] 1.70 <N2<1.75,47<V2<55,0.8<D2<1.2,10<2R1<12,4.5<2R2<5.2;

[0029] 1.6 <N3<1.65,60<V3<75,0.8<D3<1.2,12<3R1<15,3<3R2<3.5;

[0030] 2 <N4<2.1,17<V4<20,3<D4<3.5,-18<4R1<-20,-25<4R2<-30;

[0031] 1.45 <N5<1.52,80<V5<100,4<D5<4.5,-25<5R1<-30,3.5<5R2<4.5;

[0032] 1.85 <N6<1.91,30<V6<35,0.8<D6<1.2,6<6R1<8,-40<6R1<-50;

[0033] 1.85 <N7<2.05,20<V7<28,1.5<D7<2.2,7<7R1<8.5,4<7R2<5.1;

[0034] 1.45 <N8<1.55,75<V8<100,1.5<D8<2.2,4<8R1<5.1,-4<8R2-5.1;

[0035] 1.85 <N9<1.95,20<V9<25,0.5<D9<1,7<9R1<8.2,3.1<9R2<4;

[0036] 1.55 <N10<1.65,60<V10<75,2<D10<2.5,3.1<10R1<4,-6.5<10R2<-8;

[0037] Among them, N1~N10 are the refractive indices of the first lens to the tenth lens respectively, V1~V10 are the Abbe coefficients of the first lens to the tenth lens respectively, D1~D10 are the center thicknesses of the first lens to the tenth lens respectively, 1R1~10R1 are the curvature radii of the front mirror surfaces of the first lens to the tenth lens respectively, and 1R2~10R2 are the curvature radii of the rear mirror surfaces of the first lens to the tenth lens respectively.

[0038] Preferably, the first lens is made of TAF4 glass material, the second lens is made of N-LAK10 glass material, the third lens is made of N-PSK53A glass material, the fourth lens is made of E-FDS3 glass material, the fifth lens is made of FCD100 glass material, the sixth lens is made of H-ZLAF75A glass material, the seventh lens is made of H-ZLAF75A glass material, the eighth lens is made of H-FK61 glass material, the ninth lens is made of E-FDS1-W glass material, and the tenth lens is made of FCD515 glass material.

[0039] Preferably, the fisheye lens further comprises a front pressure ring, a Mylar sheet, a main lens barrel, a first spacer, and a second spacer; the main lens barrel is provided with a first inner hole, a second inner hole, a third inner hole, a fourth inner hole, and a fifth inner hole which are sequentially arranged from front to back along the axial direction and whose inner diameters gradually decrease;

[0040] The first lens is installed in the first inner hole, and the second lens is installed in the second inner hole. The front pressure ring is fixedly connected to the external thread provided on the front part of the outer wall of the main lens barrel through its internal thread hole. The front end of the front pressure ring is provided with a first annular inner flange protruding in the direction of the optical axis and located at the front side of the front end of the main lens barrel for limiting the front end position of the first lens. The Mylar sheet is located between the rear end of the first lens and the annular end surface adjacent to the first inner hole and the second inner hole and separates the first lens from the second lens, so as to ensure an air gap between the first lens and the second lens.

[0041] The third lens is installed in the third inner hole, and the rear end of the second lens is stacked with the front end of the third lens;

[0042] The cemented lens group composed of the fourth lens and the fifth lens is installed in the fourth inner hole, and the rear end of the third lens is stacked with the front end of the fourth lens;

[0043] The sixth lens, the seventh lens, the eighth lens, the ninth lens, the tenth lens, the first spacer, and the second spacer are all installed in the fifth inner hole, and the rear end of the fifth lens is stacked on the front end of the sixth lens; the first spacer is located between the sixth lens and the seventh lens, and is used to ensure the air gap between the sixth lens and the seventh lens and plays a role in fixing the aperture; the second spacer is distributed between the eighth lens and the ninth lens, and is used to ensure the air gap between the eighth lens and the ninth lens; a second annular inner flange protruding in the direction of the optical axis and used to limit the rear end of the tenth lens is provided at the rear end of the inner circumferential wall of the fifth inner hole.

[0044] Preferably, a window is further provided at the rear of the main lens barrel, and the window is made of H-K9L glass material.

[0045] Compared with the previous technology, the beneficial effects of the present invention are:

[0046] 1. The present invention provides a fisheye lens, the F-thera distortion of the fisheye lens can reach +10%, the field of view angle: >190°, the application spectrum range: 400-950nm, 10 pixels / ° at the center, >19.5 pixels / ° at the edge, the pixel size of the applicable sensor: >1.5um, and the fisheye lens can be applied to environments with high requirements for edge images.

[0047] 2. A fish-eye lens according to the present invention, the ratio of the focal length f of the fish-eye lens to the focal length f1 of the front lens group is: -3.6 < f / f1 < 4.2, and the ratio of f to the focal length f2 of the rear lens group is: 3.4 < f / f2 < 5.5; such a distribution of optical power has two advantages: First, it can make the cross-sectional area of the oblique light beam much larger than that of the axial light beam, which can also be called coma, so as to enhance the illumination at the edge of the image plane. The overall illumination uniformity of the image plane is better; Second, it can generate a long working distance, which is beneficial to the structural design and alignment.

[0048] 3. In the fish-eye lens according to the present invention, the curvature radii of the first lens, the second lens, and the third lens are all small, and each bears a certain amount of distortion aberration of the system. The small curvature radius value can ensure an increase in the main incident angle at the edge, ensure a smooth transition of light, and effectively ensure that the light can be separated as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is the optical path diagram of the existing fish-eye lens;

[0050] Figure 2 is the field curvature and F-thera distortion diagram of the existing fish-eye lens;

[0051] Figure 3 is the Seidel aberration diagram of the existing fish-eye lens;

[0052] Figure 4 is the structural schematic diagram of the fish-eye lens according to the present invention;

[0053] Figure 5 is the optical path diagram of the fish-eye lens according to the present invention;

[0054] Figure 6 is the field curvature and F-thera distortion diagram of the fish-eye lens according to the present invention;

[0055] Figure 7 is the Seidel aberration diagram of the fish-eye lens according to the present invention;

[0056] Figure 8 is the MTF diagram of the fish-eye lens according to the present invention;

[0057] Fig. 9 is the spot diagram of the fish-eye lens according to the present invention.

[0058] Reference numeral description: 1 - front retaining ring, 2 - mylar sheet, 3 - main barrel, 4 - first spacer ring, 5 - second spacer ring, A - first lens, B - second lens, C - third lens, D - fourth lens, E - fifth lens, F - sixth lens, G - seventh lens, H - eighth lens, J - ninth lens, K - tenth lens. DETAILED DESCRIPTION OF THE INVENTION

[0059] The following is a detailed description of the present invention with reference to the accompanying drawings:

[0060] As Figure 4-9 shown, a fish-eye lens, characterized in that it comprises a front lens group, a diaphragm, and a rear lens group arranged in sequence along the light incident direction, and the ratio of the focal length f of the fish-eye lens to the focal length f1 of the front lens group is: -4.2 < f / f1 < -3.6, and the ratio of the focal length f of the fish-eye lens to the focal length f2 of the rear lens group is: 3.4 < f / f2 < 5.5.

[0061] The focal length f1 of the front lens group is: -4 mm to -6 mm, and the front lens group comprises a first lens A, a second lens B, a third lens C, a fourth lens D, a fifth lens E, and a sixth lens F arranged in sequence along the light incident direction;

[0062] The air gap between the first lens A and the second lens B is: 2 mm to 3 mm;

[0063] The air gap between the second lens B and the third lens C is: 2 mm to 3 mm;

[0064] The air gap between the third lens C and the fourth lens D is: 1.5 mm to 2.5 mm;

[0065] The fourth lens D and the fifth lens E form a closely spaced cemented lens group;

[0066] The air gap between the fifth lens E and the sixth lens F is: 0.1 mm to 0.3 mm;

[0067] The air gap between the sixth lens F and the diaphragm is: 0.2 mm to 0.5 mm;

[0068] The focal length f2 of the rear lens group is: 5 mm to 8 mm, and the rear lens group comprises a seventh lens G, an eighth lens H, a ninth lens J, and a tenth lens K arranged in sequence along the light incident direction;

[0069] The air gap between the diaphragm and the seventh lens G is: 0 to 0.5 mm;

[0070] The seventh lens G and the eighth lens H form a closely spaced cemented lens group;

[0071] The air gap between the eighth lens H and the ninth lens J is 1 mm to 1.5 mm;

[0072] The ninth lens J and the tenth lens K form a closely spaced cemented lens group;

[0073] Each of the above lenses further satisfies the following conditions:

[0074] 1.75 <N1<1.85,40<V1<55,2<D1<3,15<1R1<20,7<1R2<8.5;

[0075] 1.70 <N2<1.75,47<V2<55,0.8<D2<1.2,10<2R1<12,4.5<2R2<5.2;

[0076] 1.6 <N3<1.65,60<V3<75,0.8<D3<1.2,12<3R1<15,3<3R2<3.5;

[0077] 2 <N4<2.1,17<V4<20,3<D4<3.5,-18<4R1<-20,-25<4R2<-30;

[0078] 1.45 <N5<1.52,80<V5<100,4<D5<4.5,-25<5R1<-30,3.5<5R2<4.5;

[0079] 1.85 <N6<1.91,30<V6<35,0.8<D6<1.2,6<6R1<8,-40<6R1<-50;

[0080] 1.85 <N7<2.05,20<V7<28,1.5<D7<2.2,7<7R1<8.5,4<7R2<5.1;

[0081] 1.45 <N8<1.55,75<V8<100,1.5<D8<2.2,4<8R1<5.1,-4<8R2-5.1;

[0082] 1.85 <N9<1.95,20<V9<25,0.5<D9<1,7<9R1<8.2,3.1<9R2<4;

[0083] 1.55 <N10<1.65,60<V10<75,2<D10<2.5,3.1<10R1<4,-6.5<10R2<-8;

[0084] Among them, N1~N10 are the refractive indices of the first lens to the tenth lens respectively, V1~V10 are the Abbe coefficients of the first lens to the tenth lens respectively, D1~D10 are the center thicknesses of the first lens to the tenth lens respectively, 1R1~10R1 are the curvature radii of the front mirror surfaces of the first lens to the tenth lens respectively, and 1R2~10R2 are the curvature radii of the rear mirror surfaces of the first lens to the tenth lens respectively.

[0085] Preferably, the first lens A is made of TAF4 glass material, the second lens B is made of N-LAK10 glass material, the third lens C is made of N-PSK53A glass material, the fourth lens D is made of E-FDS3 glass material, the fifth lens E is made of FCD100 glass material, the sixth lens F is made of H-ZLAF75A glass material, the seventh lens G is made of H-ZLAF75A glass material, the eighth lens H is made of H-FK61 glass material, the ninth lens J is made of E-FDS1-W glass material, and the tenth lens K is made of FCD515 glass material.

[0086] The cemented lens group composed of the fourth lens D and the fifth lens E is made of high refractive index flint glass and ED glass for correcting the vertical chromatic aberration of the system.

[0087] The sixth lens F is made of high refractive index glass, which bears most of the positive field curvature aberration of the system and corrects the field curvature of the system.

[0088] The rear lens group is provided with two groups of four lenses, wherein the eighth lens H and the tenth lens K are both made of ED glass material, and the entire rear lens group is used to correct the chromatic aberration of the system.

[0089] Preferably, the fisheye lens further comprises a front pressure ring 1, a Mylar sheet 2, a main lens barrel 3, a first spacer 4, and a second spacer 5; the main lens barrel 3 is provided with a first inner hole, a second inner hole, a third inner hole, a fourth inner hole, and a fifth inner hole which are sequentially arranged from front to back along the axial direction and whose inner diameters gradually decrease;

[0090] The first lens A is installed in the first inner hole, and the second lens B is installed in the second inner hole. The front pressure ring 1 is fixedly connected to the external thread provided on the front part of the outer wall of the main lens barrel 3 through its internal thread hole. The front end of the front pressure ring 1 is provided with a first annular inner flange protruding in the direction of the optical axis and located at the front side of the front end of the main lens barrel 3 for limiting the front end position of the first lens G1. The Mylar sheet 2 is located between the rear end of the first lens A and the annular end surface adjacent to the first inner hole and the second inner hole and separates the first lens A from the second lens B, so as to ensure the air gap between the first lens A and the second lens B.

[0091] The third lens C is installed in the third inner hole, and the rear end of the second lens B is stacked with the front end of the third lens C;

[0092] The cemented lens group consisting of the fourth lens D and the fifth lens E is installed in the fourth inner hole, and the rear end of the third lens C is stacked with the front end of the fourth lens D;

[0093] The sixth lens F, the seventh lens G, the eighth lens H, the ninth lens J, the tenth lens K, the first spacer 4, and the second spacer 5 are all installed in the fifth inner hole, and the rear end of the fifth lens E is stacked on the front end of the sixth lens F; the first spacer 4 is located between the sixth lens F and the seventh lens G, and is used to ensure the air gap between the sixth lens F and the seventh lens G and plays a role of fixing the aperture; the second spacer 5 is distributed between the eighth lens H and the ninth lens J, and is used to ensure the air gap between the eighth lens H and the ninth lens J; a second annular inner flange protruding in the direction of the optical axis and used to limit the rear end of the tenth lens K is provided at the rear end of the inner circumferential wall of the fifth inner hole.

[0094] Preferably, a window is further provided at the rear of the main lens barrel 3 , and the window is made of H-K9L glass material.

[0095] Figure 6 : This is a diagram of field curvature and F-thera distortion of the fisheye lens of the present invention. It can be seen from the diagram that the F-thera distortion of the fisheye lens is about 11%. Figure 7 is the Seidel aberration diagram of the fisheye lens of the present invention, Figure 8 is the MTF diagram of the fisheye lens of the present invention, Fig. 9 This is a point diagram of the fisheye lens of the present invention. It can be seen from the figures that except for the very edge, the pixel size of the rest of the field of view of the fisheye lens is less than 1.5um, and it meets the requirements for use in cameras with pixel size <1.5um.

[0096] The fisheye lens of this embodiment can achieve the following optical indicators:

[0097] 1. Focal length: 1.45mm;

[0098] 2. Aperture: F#2.4;

[0099] 3. Angle: >190°;

[0100] 4. Application spectrum range: 400-950nm;

[0101] 5. F-thera distortion>+10%, 10 pixels / ° in the center, 19.5 pixels / ° at the edge;

[0102] 6. Applicable sensor pixel size: >1.5um;

[0103] 7. Image circle diameter: >5.45mm@190°.

[0104] Although the present invention is illustrated and described by specific embodiments and their alternatives, it should be understood that various changes and modifications within the spirit and scope of the present invention can be implemented. Therefore, it should be understood that the present invention is not limited in any sense except by the limitations of the attached claims and their equivalents.

Claims

1. A fisheye lens, characterized in that: It includes a front lens group, a diaphragm, and a rear lens group arranged in sequence along the light incident direction. The ratio of the focal length f of the fish-eye lens to the focal length f1 of the front lens group is: -4.2 < f / f1 < -3.6, and the ratio of the focal length f of the fish-eye lens to the focal length f2 of the rear lens group is: 3.4 < f / f2 < 5.5; The focal length f1 of the front lens group is: -4 mm to -6 mm. The front lens group includes a first lens (A), a second lens (B), a third lens (C), a fourth lens (D), a fifth lens (E), and a sixth lens (F) arranged in sequence along the light incident direction; The air gap between the first lens (A) and the second lens (B) is: 2 mm to 3 mm; The air gap between the second lens (B) and the third lens (C) is: 2 mm to 3 mm; The air gap between the third lens (C) and the fourth lens (D) is: 1.5 mm to 2.5 mm; The fourth lens (D) and the fifth lens (E) form a closely - contacted cemented lens group; The air gap between the fifth lens (E) and the sixth lens (F) is: 0.1 mm to 0.3 mm; The air gap between the sixth lens (F) and the diaphragm is: 0.2 mm to 0.5 mm; The focal length f2 of the rear lens group is: 5 mm to 8 mm. The rear lens group includes a seventh lens (G), an eighth lens (H), a ninth lens (J), and a tenth lens (K) arranged in sequence along the light incident direction; The air gap between the diaphragm and the seventh lens (G) is: 0 to 0.5 mm; The seventh lens (G) and the eighth lens (H) form a closely - contacted cemented lens group; The air gap between the eighth lens (H) and the ninth lens (J) is 1 mm to 1.5 mm; The ninth lens (J) and the tenth lens (K) form a closely - contacted cemented lens group; Each of the above - mentioned lenses also satisfies the following conditions: 1.75 < N1 < 1.85, 40 < V1 < 55, 2 < D1 < 3, 15 < 1R1 < 20, 7 < 1R2 < 8.5; 1.70 < N2 < 1.75, 47 < V2 < 55, 0.8 < D2 < 1.2, 10 < 2R1 < 12, 4.5 < 2R2 < 5.2; 1.6 < N3 < 1.65, 60 < V3 < 75, 0.8 < D3 < 1.2, 12 < 3R1 < 15, 3 < 3R2 < 3.5; 2 < N4 < 2.1, 17 < V4 < 20, 3 < D4 < 3.5, -18 < 4R1 < -20, -25 < 4R2 < -30; 1.45 < N5 < 1.52, 80 < V5 < 100, 4 < D5 < 4.5, -25 < 5R1 < -30, 3.5 < 5R2 < 4.5; 1.85 < N6 < 1.91, 30 < V6 < 35, 0.8 < D6 < 1.2, 6 < 6R1 < 8, -40 < 6R1 < -50; 1.85 < N7 < 2.05, 20 < V7 < 28, 1.5 < D7 < 2.2, 7 < 7R1 < 8.5, 4 < 7R2 < 5.1; 1.45 <N8<1.55,75<V8<100,1.5<D8<2.2,4<8R1<5.1,-4<8R2-5.1;1.85<N9<1.95,20<V9<25,0.5<D9<1,7<9R1<8.2,3.1<9R2<4;1.55<N10<1.65,60<V10<75,2<D10<2.5,3.1<10R1<4,-6.5<10R2<-8; Among them, N1~N10 are the refractive indices of the first lens to the tenth lens respectively, V1~V10 are the Abbe coefficients of the first lens to the tenth lens respectively, D1~D10 are the center thicknesses of the first lens to the tenth lens respectively, 1R1~10R1 are the curvature radii of the front mirror surfaces of the first lens to the tenth lens respectively, and 1R2~10R2 are the curvature radii of the rear mirror surfaces of the first lens to the tenth lens respectively.

2. The fisheye lens according to claim 1, characterized in that: The first lens (A) is made of TAF4 glass material, the second lens (B) is made of N-LAK10 glass material, the third lens (C) is made of N-PSK53A glass material, the fourth lens (D) is made of E-FDS3 glass material, the fifth lens (E) is made of FCD100 glass material, the sixth lens (F) is made of H-ZLAF75A glass material, the seventh lens (G) is made of H-ZLAF75A glass material, the eighth lens (H) is made of H-FK61 glass material, the ninth lens (J) is made of E-FDS1-W glass material, and the tenth lens (K) is made of FCD515 glass material.

3. The fisheye lens according to any one of claims 1 to 2, characterized in that: The fisheye lens further comprises a front pressure ring (1), a Mylar sheet (2), a main lens barrel (3), a first spacer ring (4), and a second spacer ring (5); the main lens barrel (3) is provided with a first inner hole, a second inner hole, a third inner hole, a fourth inner hole, and a fifth inner hole arranged in sequence from front to back along the axial direction and with gradually decreasing inner diameters; The first lens (A) is installed in the first inner hole, and the second lens (B) is installed in the second inner hole. The front pressure ring (1) is fixedly connected to the external thread provided on the front part of the outer wall of the main lens barrel (3) through its internal thread hole. The front end of the front pressure ring (1) is provided with a first annular inner flange protruding in the direction of the optical axis and located at the front side of the front end of the main lens barrel (3) for limiting the front end position of the first lens (A). The Mylar sheet (2) is located between the rear end of the first lens (A) and the annular end surface adjacent to the first inner hole and the second inner hole and separates the first lens (A) from the second lens (B), so as to ensure an air gap between the first lens (A) and the second lens (B). The third lens (C) is installed in the third inner hole, and the rear end of the second lens (B) is stacked with the front end of the third lens (C); The cemented lens group composed of the fourth lens (D) and the fifth lens (E) is installed in the fourth inner hole, and the rear end of the third lens (C) is stacked with the front end of the fourth lens (D); The sixth lens (F), the seventh lens (G), the eighth lens (H), the ninth lens (J), the tenth lens (K), the first spacer (4), and the second spacer (5) are all installed in the fifth inner hole, and the rear end of the fifth lens (E) is stacked on the front end of the sixth lens (F); the first spacer (4) is located between the sixth lens (F) and the seventh lens (G), and is used to ensure the air gap between the sixth lens (F) and the seventh lens (G) and plays a role in fixing the aperture; the second spacer (5) is distributed between the eighth lens (H) and the ninth lens (J), and is used to ensure the air gap between the eighth lens (H) and the ninth lens (J); and a second annular inner flange protruding in the direction of the optical axis and used to limit the rear end of the tenth lens (K) is provided at the rear end of the inner peripheral wall of the fifth inner hole.

4. The fisheye lens according to claim 3, characterized in that: A window is also provided at the rear of the main lens barrel (3), wherein the window is made of H-K9L glass material.

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