Super wide angle low distortion long focus fish eye optical system
Technical Field
The invention relates to the field of optical systems, in particular to an ultra-wide-angle low-distortion long-focus fisheye optical system.
Background
With the advent of the information age, people want to obtain wider spatial information so as to more fully and comprehensively sense the surrounding environment. The fisheye lens has the imaging characteristic of an ultra-wide angle, has great advantages in the aspect of acquiring spatial information, and is widely concerned by scientific researchers. However, the existing super-wide fisheye optical system has the disadvantages of large distortion, short focal length, etc., and the method of increasing the number of optical elements or using aspheric surfaces is also commonly adopted to improve the imaging quality.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides an ultra-wide angle low-distortion long-focus fisheye optical system, which solves the problems of large distortion, short focal length, complex structure, high research and development cost and the like of the conventional ultra-wide angle fisheye optical system.
The technical scheme adopted by the invention for solving the technical problem is as follows:
the utility model provides a long focus fish eye optical system of super wide angle low distortion, is equipped with from the object plane to image plane along the optical axis in proper order: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens, wherein the focal power of the first lens is negative, -0.26< f/f1< -0.22;
the power of the second lens is negative, -0.32< f/f2< -0.27;
the third lens has a positive optical power of 0.17< f/f3< 0.25;
the focal power of the fourth lens is positive, 0.16< f/f4< 0.22;
the power of the fifth lens is positive, 0.05< f/f5< 0.13;
the power of the sixth lens is positive, 0.50< f/f6< 0.70;
the power of the seventh lens is negative, -0.70< f/f7< -0.45; 0.025< f/f67< 0.085;
where f is a focal length of the entire optical system, f1 is a focal length of the first lens, f2 is a focal length of the second lens, f3 is a focal length of the third lens, f4 is a focal length of the fourth lens, f5 is a focal length of the fifth lens, f6 is a focal length of the sixth lens, and f67 is a combined focal length of the sixth lens and the seventh lens.
Preferably, the seventh lens and the sixth lens are cemented together to form a combined lens having a positive optical power of 0.025< f/f67< 0.085.
Preferably, the full field angle of the optical system is greater than or equal to 1800The focal length is 10.0mm, the relative aperture F/2.8, the relative illumination is greater than 0.65, and the relative distortion is less than 1%.
Preferably, the material of the first lens is H-ZLAF52A, the material of the second lens is H-FK61, the material of the third lens is H-LAK52, the material of the fourth lens is H-ZK9B, the material of the fifth lens is H-LAK52, the material of the sixth lens is H-FK61, and the material of the seventh lens is H-ZF7 LA.
Preferably, a diaphragm is arranged between the fifth lens and the fourth lens.
Preferably, the radius of curvature of the incident surface of the first lens is 65.0mm, the radius of curvature of the emergent surface is 21.9mm, the center thickness is 2.5mm, and the clear aperture of the lens is phi 77.5 mm; the curvature radius of the incident surface of the second lens is-146.5 mm, the curvature radius of the emergent surface of the second lens is 18.8mm, the center thickness of the second lens is 3.3mm, and the clear aperture of the second lens is phi 42.2 mm; the curvature radius of the incident surface of the third lens is 84.5mm, the curvature radius of the emergent surface of the third lens is-65.3 mm, the center thickness of the third lens is 6.0mm, and the clear aperture of the third lens is phi 26.4 mm; the curvature radius of the incident surface of the fourth lens is 15.4mm, the curvature radius of the emergent surface of the fourth lens is 25.9mm, the center thickness of the fourth lens is 2.9mm, and the light-passing aperture of the fourth lens is phi 20.0 mm; the curvature radius of the incident surface of the fifth lens is-29.0 mm, the curvature radius of the emergent surface of the fifth lens is-23.8 mm, the center thickness of the fifth lens is 4.2mm, and the clear aperture of the fifth lens is phi 10.5 mm; the curvature radius of the incident surface of the sixth lens is 32.6mm, the curvature radius of the emergent surface of the sixth lens is-10.8 mm, the center thickness of the sixth lens is 4.7mm, and the clear aperture of the sixth lens is phi 14.4 mm; the curvature radius of the incident surface of the seventh lens is-10.8 mm, the curvature radius of the emergent surface of the seventh lens is-39.3 mm, the center thickness of the seventh lens is 1.7mm, and the clear aperture of the seventh lens is phi 14.7 mm.
Preferably, the distance between the first lens and the second lens is 21.1 mm; the distance between the second lens and the third lens is 25.6 mm; the distance between the third lens and the fourth lens is 1.6 mm; the distance between the fourth lens and the aperture diaphragm is 8.1 mm; the distance between the aperture diaphragm and the fifth lens is 1.1 mm; the distance between the fifth lens and the sixth lens is 0.1 mm; the distance between the seventh lens and the image plane is 22.0 mm.
The invention has the beneficial effects that: the invention is composed of seven global surface lenses, the structure is simple, and the research and development cost is low; adopts different lenses which are mutually combined and reasonably distributed to have the focal power of 1800The super wide angle, low distortion, long focal length and high transmission function, and is suitable for security, military and photography.
Drawings
FIG. 1 is a schematic diagram of a super wide angle low distortion long focal length fisheye optical system of the invention;
FIG. 2 is a distortion curve diagram of an ultra-wide angle low distortion long focal length fisheye optical system of the invention.
In the figure: 1. the lens system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an aperture diaphragm, an aperture stop, an imaging surface and a fourth lens, wherein the first lens is 2, the second lens is 3, the third lens is 4, the fourth lens is 5, the fifth lens is 6, the sixth lens is 7, the seventh lens is 8, the aperture diaphragm is 9.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples.
As shown in fig. 1, the super-wide angle global surface fisheye optical system is sequentially provided with, from an object plane to an image plane along an optical axis: a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, an aperture stop 8, a fifth lens 5, a sixth lens 6, a seventh lens 7, and an image plane 9. The focal powers of the first lens 1, the second lens 2 and the seventh lens 7 are all negative, and the focal powers of the third lens 3, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are all positive.
In a specific embodiment of this embodiment, the seventh lens 7 and the sixth lens 6 are cemented together to form a combined lens, and the focal power of the combined lens is positive. Simple structure, can guarantee good optical property.
As a specific embodiment of the present solution, without limitation, each lens of the optical system satisfies the following conditions:
-0.26<f/f1<-0.22;
-0.32<f/f2<-0.27;
0.17<f/f3<0.25;
0.16<f/f4<0.22;
0.05<f/f5<0.13;
0.50<f/f6<0.70;
-0.70<f/f7<-0.45;
0.025<f/f67<0.085;
where f is a focal length of the entire optical system, f1 is a focal length of the first lens 1, f2 is a focal length of the second lens 2, f3 is a focal length of the third lens 3, f4 is a focal length of the fourth lens 4, f5 is a focal length of the fifth lens 5, f6 is a focal length of the sixth lens 6, f7 is a focal length of the seventh lens 7, and f67 is a combined focal length of the sixth lens and the seventh lens.
All the lenses of the invention are spherical lenses, thus reducing the processing difficulty of optical elements and simultaneously reducing the research and development cost.
Preferably, the first lens element 1 is made of H-ZLAF52A, the second lens element 2 is made of H-FK61, the third lens element 3 is made of H-LAK52, the fourth lens element 4 is made of H-ZK9B, the fifth lens element 5 is made of H-LAK52, the sixth lens element 6 is made of H-FK61, and the seventh lens element 7 is made of H-ZF7 LA.
For convenience of description, the light incident surface of the lens is used as the front surface, and the light emergent surface of the lens is used as the rear surface.
Further as a preferred embodiment, the curvature radius of the front surface of the first lens 1 is 65.0mm, the curvature radius of the rear surface is 21.9mm, the center thickness is 2.5mm, and the clear aperture of the lens is Φ 77.5 mm;
the curvature radius of the front surface of the second lens 2 is-146.5 mm, the curvature radius of the rear surface is 18.8mm, the center thickness is 3.3mm, and the clear aperture of the lens is phi 42.2 mm;
the curvature radius of the front surface of the third lens 3 is 84.5mm, the curvature radius of the rear surface is-65.3 mm, the center thickness is 6.0mm, and the clear aperture of the lens is phi 26.4 mm;
the curvature radius of the front surface of the fourth lens 4 is 15.4mm, the curvature radius of the rear surface of the fourth lens is 25.9mm, the center thickness of the fourth lens is 2.9mm, and the clear aperture of the fourth lens is phi 20.0 mm;
the curvature radius of the front surface of the fifth lens 5 is-29.0 mm, the curvature radius of the rear surface of the fifth lens is-23.8 mm, the center thickness of the fifth lens is 4.2mm, and the clear aperture of the fifth lens is phi 10.5 mm;
the curvature radius of the front surface of the sixth lens 6 is 32.6mm, the curvature radius of the rear surface is-10.8 mm, the center thickness is 4.7mm, and the clear aperture of the lens is phi 14.4 mm;
the curvature radius of the front surface of the seventh lens 7 is-10.8 mm, the curvature radius of the rear surface is-39.3 mm, the center thickness is 1.7mm, and the clear aperture of the lens is phi 14.7 mm.
Further as a preferred embodiment, the distance between the first lens 1 and the second lens 2 is 21.1 mm; the distance between the second lens 2 and the third lens 3 is 25.6 mm; the distance between the third lens 3 and the fourth lens 4 is 1.6 mm; the distance between the fourth lens 4 and the aperture diaphragm 8 is 8.1 mm; the distance between the aperture diaphragm 8 and the fifth lens 5 is 1.1 mm; the distance between the fifth lens 5 and the sixth lens 6 is 0.1 mm; the distance of the seventh lens 7 from the image plane 9 is 22.0 mm.
The specific parameters of the optical system are as follows:
focal length 10.0 mm; relative pore diameter F/2.8; full field angle 1800。
Fig. 2 is a distortion curve diagram of the optical system of the present invention, and it can be seen from fig. 2 that the distortion of the optical system is less than 0.15% in the whole field of view.
While the preferred embodiments of the present invention have been illustrated and described, it will be understood by those skilled in the art that the present invention is not limited to the details of the embodiments shown and described, but is capable of numerous equivalents and substitutions without departing from the spirit of the invention and its scope is defined by the claims appended hereto.