CN111025601B

CN111025601B - Wide-angle large-aperture athermal day and night lens and using method thereof

Info

Publication number: CN111025601B
Application number: CN201911418413.0A
Authority: CN
Inventors: 潘慧峰; 肖维军; 张荣曜
Original assignee: Fujian Forecam Optics Co Ltd
Current assignee: Fujian Forecam Optics Co Ltd
Priority date: 2019-12-31
Filing date: 2019-12-31
Publication date: 2021-12-28
Anticipated expiration: 2039-12-31
Also published as: CN111025601A

Abstract

The invention provides a wide-angle large-aperture athermalized day-night dual-purpose lens and a using method thereof, wherein the wide-angle large-aperture athermalized day-night dual-purpose lens comprises a front group A, a diaphragm C, a rear group B, a parallel flat plate and an image surface which are sequentially arranged along the incident direction of light rays from left to right, the front group A comprises a first meniscus negative lens, a second meniscus negative lens and a third biconvex positive lens which are sequentially arranged from left to right, and the rear group B comprises a first biconvex positive lens, a second biconvex positive lens, a third biconcave negative lens and a fourth biconvex positive lens which are sequentially arranged from left to right.

Description

Wide-angle large-aperture athermal day and night lens and using method thereof

Technical Field

The invention relates to a wide-angle large-aperture athermal day and night lens and a using method thereof.

Background

In recent years, with the wider application range of the camera lens, people have higher requirements on the pixel and athermalization of the lens and the day and night use. However, the existing lens generally has the following disadvantages: the effect of no heating and dual-purpose day and night is not good, and the effect of no heating and dual-purpose day and night can be achieved only by additionally arranging one or even a plurality of lenses; the aperture is small, the requirement of the lowest imaging illumination of the CCD chip can not be met under low illumination, clear imaging can not be realized, the overall dimension is large, and the occupied space is large.

Disclosure of Invention

The invention improves the problems, namely the technical problems to be solved by the invention are that the existing athermalized and day and night dual-purpose lens cannot meet the requirement of the minimum imaging illumination of a CCD chip under low illumination, cannot clearly image, has larger overall dimension and occupies more space.

The specific embodiment of the invention is as follows: the utility model provides a dual-purpose camera lens of wide angle big light ring athermalization day and night, includes preceding group A, diaphragm C, back group B, parallel flat board, image plane that sets gradually along light from left right side incident direction, preceding group A is from left right side including the first meniscus negative lens, second meniscus negative lens, the biconvex positive lens that set gradually, and back group B is from left right side including the first biconvex positive lens, the biconvex positive lens of second, the biconcave negative lens, the biconvex positive lens of fourth that set gradually.

Further, the air space between the first negative meniscus lens of the front group a and the second negative meniscus lens of the front group a is 2.8mm to 3.3mm, the air space between the second negative meniscus lens of the front group a and the third double convex positive meniscus lens of the front group a is 0.07mm to 0.1mm, the air space between the third double convex positive meniscus lens of the front group a and the first double convex positive lens of the rear group B is 0.7mm to 1.3mm, the air space between the first double convex positive lens of the rear group B and the second double convex positive lens of the rear group B is 0.15mm to 0.25mm, the air space between the second double convex positive lens of the rear group B and the third double concave negative meniscus lens of the rear group B is 0.4mm to 0.45mm, and the air space between the third double concave negative meniscus lens of the rear group B and the fourth positive lens of the rear group B is 0.1mm to 0.25 mm.

Further, setting the total focal length of the optical system to f, sequentially setting the focal lengths of the first negative meniscus lens of the front group a, the second negative meniscus lens of the front group a, the third double convex positive lens of the front group a, the first double convex positive lens of the rear group B, the second double convex positive lens of the rear group B, the third double concave negative lens of the rear group B, and the fourth double convex positive lens of the rear group B to f1, f2, f3, f4, f5, f6 and f7 along the incident direction of the light, wherein the focal lengths of the lenses are as follows: -2.2< f1/f < -1.9, -2.1< f2/f < -1.8, -3 < f3/f <4, -2 < f4/f <2.5, -1.9 < f5/f <2.3, -1.5< f6/f < -1, 1< f7/f <2.

Furthermore, the first negative meniscus lens, the second negative meniscus lens and the third double convex positive lens of the front group A are all plastic aspheric lenses, the first double convex positive lens of the rear group B is a glass spherical surface, and the rest are plastic aspheric lenses.

The invention also comprises a working method of the wide-angle large-aperture athermal day and night lens, which comprises the wide-angle large-aperture athermal day and night lens, when light enters, the light path sequentially enters the front group A, the diaphragm C, the rear group B and the parallel flat plate, and finally imaging is carried out on the image surface, when the light passes through the front group A, the first lens of the front group A can converge the incident angle of the light, and when the light passes through the other lenses, aberration balance can be carried out; the first biconvex positive lens adopts glass with low refractive index and high Abbe number, and the third biconcave negative lens adopts plastic with high refractive index and low Abbe number, so that the second-order spectrum and spherical aberration are corrected.

Compared with the prior art, the invention has the following beneficial effects: the lens has simple structure, small volume, low cost, no thermalization, dual purposes of day and night, large aperture and high resolution, and can be matched with a CCD or CMOS chip with 600 ten thousand pixels for use.

Drawings

FIG. 1 is a schematic diagram of an optical system according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an MTF value of 20 ° ambient visible light according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of an MTF value of an ambient visible light of-30 ° in accordance with an embodiment of the present invention;

FIG. 4 is a schematic diagram of an MTF value of 70 ° ambient visible light according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of a defocused MTF value of visible light according to an embodiment of the present invention;

FIG. 6 is a schematic diagram of an infrared defocus MTF value according to an embodiment of the present invention;

in the figure: 110 — first negative meniscus lens; 120-a second negative meniscus lens; 130-a third biconvex positive lens; 210-a first biconvex positive lens; 220-a second biconvex positive lens; 230-a third biconcave negative lens; 240-a fourth biconvex positive lens; 300-a diaphragm; 400-parallel plates; 500-IMA image plane.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1-6, a wide-angle large-aperture athermalized day-night dual-purpose lens comprises a front group A, a diaphragm C, a rear group B, a parallel flat plate and an image surface which are sequentially arranged along the incident direction of light from left to right, wherein the front group A comprises a first meniscus negative lens, a second meniscus negative lens and a third biconvex positive lens which are sequentially arranged from left to right, and the rear group B comprises a first biconvex positive lens, a second biconvex positive lens, a third biconcave negative lens and a fourth biconvex positive lens which are sequentially arranged from left to right.

In this embodiment, the total focal length of the optical system is set to f, and the focal lengths of the first negative meniscus lens of the front group a, the second negative meniscus lens of the front group a, the third double convex positive lens of the front group a, the first double convex positive lens of the rear group B, the second double convex positive lens of the rear group B, the third double concave negative lens of the rear group B, and the fourth double convex positive lens of the rear group B are sequentially set to f1, f2, f3, f4, f5, f6, and f7 along the incident direction of the light, and the focal lengths of the lenses are as follows: -2.2< f1/f < -1.9, -2.1< f2/f < -1.8, -3 < f3/f <4, -2 < f4/f <2.5, -1.9 < f5/f <2.3, -1.5< f6/f < -1, 1< f7/f <2.

In this embodiment, the first negative meniscus lens, the second negative meniscus lens and the third double convex positive lens of the front group a are all plastic aspheric lenses, the first double convex positive lens of the rear group B is a glass sphere, and the rest are plastic aspheric lenses.

The lenses shown from left to right in fig. 1 are shown in table 1, with specific lens parameters as follows:

in this embodiment, the aspherical surface has the following surface equation:

wherein z is a distance vector from a vertex of the aspheric surface when the aspheric surface is at a position with a height of R along the optical axis direction, c is a curvature of a paraxial of the aspheric surface, c =1/R, R is a curvature radius, c is a reciprocal of the curvature radius, k is a conic coefficient, a1 is an aspheric 2 nd order coefficient, a2 is an aspheric 4 th order coefficient, a3 is an aspheric 6 th order coefficient, a4 is an aspheric 8 th order coefficient, a5 is an aspheric 10 th order coefficient, a6 is an aspheric 12 th order coefficient, a7 is an aspheric 14 th order coefficient, a8 is an aspheric 16 th order coefficient, and the aspheric coefficients of the 3-aspheric lens are as follows:

table two: items 2, 3, 5, 6, 7 are as follows:

table three: 11 th, 12 th, 13 th are as follows:

in this embodiment, the technical indexes of the optical system are as follows: (1) focal length: EFFL =4.0 mm; (2) f number = 1.4; (3) the field angle: 2w is more than or equal to 110 degrees; (4) the diameter of the imaging circle is more than phi 6.6; (5) working spectral range: 430 nm-850 nm; (6) the total optical length TTL is less than or equal to 24mm, and the optical rear intercept is more than or equal to 5.5 mm; (7) F-Theta distortion = -40%; (8) the lens is suitable for a 4K pixel high-resolution CCD or CMOS camera.

An operating method of a wide-angle large-aperture athermal day and night lens, comprising the following steps: when light enters, a light path sequentially enters the front group A100, the diaphragm C300, the rear group B200 and the parallel flat plate 400, and finally imaging is carried out on the IMA image surface 500, when the light passes through the front group A100, one lens of the front group A100 can converge the incident angle of the light, and when the light passes through the other lenses, aberration balance can be carried out; the B210 adopts glass with low refractive index and high Abbe number, and the A130 adopts plastic with high refractive index and low Abbe number, so that the secondary spectrum and spherical aberration are well corrected, and the lens system is well corrected for chromatic aberration through reasonable matching of materials. When the lens is designed, the visible spectrum of F, C, D is adopted, and the F/# is set to be 1.4, so that the clear aperture is large, and rapid and clear imaging can still be realized at low illumination. By reasonably distributing the focal power of 7 lenses, the total optical length of the lens is compressed while small distortion is kept, so that the optical system has a compact structure and is beneficial to saving the use cost.

Any embodiment disclosed herein above is meant to disclose, unless otherwise indicated, all numerical ranges disclosed as being preferred, and any person skilled in the art would understand that: the preferred ranges are merely those values which are obvious or representative of the technical effect which can be achieved. Since the numerical values are too numerous to be exhaustive, some of the numerical values are disclosed in the present invention to illustrate the technical solutions of the present invention, and the above-mentioned numerical values should not be construed as limiting the scope of the present invention.

If the terms "first," "second," etc. are used herein to define parts, those skilled in the art will recognize that: the terms "first" and "second" are used merely to distinguish one element from another in a descriptive sense and are not intended to have a special meaning unless otherwise stated.

Meanwhile, if the invention as described above discloses or relates to parts or structural members fixedly connected to each other, the fixedly connected parts can be understood as follows, unless otherwise stated: a detachable fixed connection (for example using bolts or screws) is also understood as: non-detachable fixed connections (e.g. riveting, welding), but of course, fixed connections to each other may also be replaced by one-piece structures (e.g. manufactured integrally using a casting process) (unless it is obviously impossible to use an integral forming process).

In addition, terms used in any technical solutions disclosed in the present invention to indicate positional relationships or shapes include approximate, similar or approximate states or shapes unless otherwise stated.

Any part provided by the invention can be assembled by a plurality of independent components or can be manufactured by an integral forming process.

Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present invention and not to limit the same; although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that: modifications to the specific embodiments of the invention or equivalent substitutions for parts of the technical features may be made; without departing from the spirit of the present invention, it is intended to cover all aspects of the invention as defined by the appended claims.

Claims

1. The utility model provides a dual-purpose camera lens of wide angle big light ring athermalization day night which characterized in that: the optical lens comprises a front group A, a diaphragm C, a rear group B, a parallel flat plate and an image surface which are sequentially arranged along the incident direction of light rays from left to right, wherein the front group A comprises a first meniscus negative lens, a second meniscus negative lens and a third biconvex positive lens which are sequentially arranged from left to right, and the rear group B comprises a first biconvex positive lens, a second biconvex positive lens, a third biconcave negative lens and a fourth biconvex positive lens which are sequentially arranged from left to right;

the air space between the first negative meniscus lens of the front group A and the second negative meniscus lens of the front group A is 2.8-3.3 mm, the air space between the second negative meniscus lens of the front group A and the third double convex positive meniscus lens of the front group A is 0.07-0.1 mm, the air space between the third double convex positive meniscus lens of the front group A and the first double convex positive meniscus lens of the rear group B is 0.7-1.3 mm, the air space between the first double convex positive meniscus lens of the rear group B and the second double convex positive meniscus lens of the rear group B is 0.15-0.25 mm, the air space between the second double convex positive meniscus lens of the rear group B and the third double concave negative meniscus lens of the rear group B is 0.4-0.45 mm, and the air space between the third double concave negative meniscus lens of the rear group B and the fourth double convex positive meniscus lens of the rear group B is 0.1-0.25 mm;

setting the total focal length of the optical system as f, sequentially setting the focal lengths of a first negative meniscus lens of the front group A, a second negative meniscus lens of the front group A, a third double convex positive lens of the front group A, a first double convex positive lens of the rear group B, a second double convex positive lens of the rear group B, a third double concave negative lens of the rear group B and a fourth double convex positive lens of the rear group B as f1, f2, f3, f4, f5, f6 and f7 along the incident direction of light rays, wherein the focal lengths of the lenses are as follows: -2.2< f1/f < -1.9, -2.1< f2/f < -1.8, -3 < f3/f <4, -2 < f4/f <2.5, -1.9 < f5/f <2.3, -1.5< f6/f < -1, 1< f7/f <2.

2. The wide-angle large-aperture athermal day-night lens of claim 1, wherein: the first negative meniscus lens, the second negative meniscus lens and the third double convex positive lens of the front group A are all plastic aspheric lenses, the first double convex positive lens of the rear group B is a glass spherical surface, and the rest are plastic aspheric lenses.

3. A method of operating a wide-angle large-aperture athermal day-night lens, comprising the wide-angle large-aperture athermal day-night lens of claim 2, wherein: when light enters, the light path sequentially enters the front group A, the diaphragm C, the rear group B and the parallel flat plate, and finally imaging is carried out on an image surface; the first biconvex positive lens adopts glass with low refractive index and high Abbe number, and the third biconcave negative lens adopts plastic with high refractive index and low Abbe number, so that the second-order spectrum and spherical aberration are corrected.