CN215867313U

CN215867313U - 2.8mm large-aperture day and night dual-purpose glass-plastic fixed-focus optical system

Info

Publication number: CN215867313U
Application number: CN202121467577.5U
Authority: CN
Inventors: 戴敏林; 罗杰; 黄锦煖; 胡青平
Original assignee: Fujian Forecam Optics Co Ltd
Current assignee: Fujian Forecam Optics Co Ltd
Priority date: 2021-06-30
Filing date: 2021-06-30
Publication date: 2022-02-18
Anticipated expiration: 2031-06-30

Abstract

The utility model relates to a 2.8mm large-aperture and day and night dual-purpose glass-plastic fixed-focus optical system, which comprises a biconcave plastic aspheric lens A-1, a meniscus plastic aspheric lens A-2, a biconvex glass lens A-3, a diaphragm C, a meniscus plastic aspheric lens B-1 and a biconvex plastic aspheric lens B-2 which are sequentially arranged at intervals from front to back along an incident light path; the meniscus plastic aspheric lens A-1, the meniscus plastic aspheric lens A-2 and the biconvex glass lens A-3 form a front group A with negative focal power, and the meniscus plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 form a rear group B with positive focal power; by using 4 pieces of plastic high-order aspheric surface to correct spherical aberration, chromatic aberration and high-order aberration, and reasonably calculating the focal power of each piece of aspheric surface, the focal point does not deviate in high-temperature and low-temperature environments, and the effect of day and night focus adjustment is achieved.

Description

2.8mm large-aperture day and night dual-purpose glass-plastic fixed-focus optical system

Technical Field

The utility model relates to a 2.8mm large-aperture day and night dual-purpose glass-plastic fixed-focus optical system, and relates to the field of security and protection.

Background

Various fixed-focus lenses are applied to security systems in the market at present, but the F number of most lenses is larger than 2.0, the aperture is small, and in order to improve the performance and improve the pixel, more glass lenses are generally used to achieve higher-definition image quality, so that the product cost is greatly increased, and the product popularization difficulty is improved. Moreover, because most of the glass spherical surface designs are used, the processing precision of the glass spherical surface is poor, the cost is high, the lens can hardly meet the market demand in terms of pixel, performance and cost, and the prime focus lens with low cost, high image quality, large aperture and day and night dual-purpose is rarely used in the security industry.

SUMMERY OF THE UTILITY MODEL

In view of the defects of the prior art, the utility model aims to provide a glass-plastic prime optical system with a large aperture of 2.8mm and dual purposes of day and night, which has a simple and reasonable structure and is low in cost.

In order to solve the technical problems, the technical scheme of the utility model is as follows: a2.8 mm large-aperture and day and night dual-purpose glass-plastic fixed-focus optical system comprises a biconcave plastic aspheric lens A-1, a meniscus plastic aspheric lens A-2, a biconvex glass lens A-3, a diaphragm C, a meniscus plastic aspheric lens B-1 and a biconvex plastic aspheric lens B-2 which are sequentially arranged at intervals from front to back along an incident light path; the biconcave plastic aspheric lens A-1, the falcate plastic aspheric lens A-2 and the biconvex glass lens A-3 form a front group A with negative focal power, and the falcate plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 form a rear group B with positive focal power.

Further, the air space between the biconcave plastic aspheric lens a-1 and the meniscus plastic aspheric lens a-2 is 2.36mm, the air space between the meniscus plastic aspheric lens a-2 and the biconvex glass lens a-3 is 1.31mm, the air space between the biconvex glass lens a-3 and the meniscus plastic aspheric lens B-1 is 1.12mm, and the air space between the meniscus plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 is 0.13 mm.

Further, setting the focal length of an optical system of the lens to be f, and setting the focal lengths of the system shared by the biconcave plastic aspheric lens A-1, the meniscus plastic aspheric lens A-2, the biconvex glass lens A-3, the diaphragm C, the meniscus plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 to be f1, f2, f3, f4 and f5 respectively; wherein f satisfies the following condition: -6mm < f1< -5 mm; 35mm < f2<37 mm; 7mm < f3<9 mm; -8mm < f4< -6 mm; 5mm < f5<7 mm.

Furthermore, the biconcave plastic aspheric lens A-1, the falcate plastic aspheric lens A-2, the falcate plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 are made of plastic materials.

Furthermore, a filter D is arranged on the rear side of the biconvex plastic aspheric lens B-2.

Compared with the prior art, the utility model has the following beneficial effects: (1) by using 4 pieces of plastic high-order aspheric surface to correct spherical aberration, chromatic aberration and high-order aberration, and reasonably calculating the focal power of each piece of aspheric surface, the focal point does not deviate in high-temperature and low-temperature environments, and the effect of day and night focus adjustment is achieved. (2) By utilizing a high-order plastic aspheric surface technology, the precision is improved, the structure is simplified, the high-definition camera shooting level is realized at ultralow cost, high-quality pixels can be achieved in the daytime, high-definition image quality is achieved under the condition of insufficient light or at night, and perfect imaging can be still realized in severe environments with different temperatures; (3) through using two slice disconnect-type aspheres of two back groups of preceding group, positive and negative focal power matches simultaneously, simple structure, reasonable has solved that current tight shot definition is not enough, the aperture is less, adopt many lens structures to lead to cost increase, and the structure is complicated simultaneously, can't realize the problem of light small-size tight shot.

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

Drawings

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

FIG. 2 is the functional value of MTF under visible light of the optical system;

FIG. 3 shows the functional values of MTF of the optical system under 850nm infrared light;

FIG. 4 is the MTF defocus curve under visible light of the optical system;

FIG. 5 is the MTF defocus curve of the optical system under 850nm infrared light;

FIG. 6 shows the functional values of MTF of the optical system at-30 deg.C;

FIG. 7 shows the functional values of MTF of the optical system at a high temperature of 70 ℃;

in the figure: a-1 biconcave plastic aspheric lens A-1, A-2 meniscus plastic aspheric lens A-2, A-3 biconvex glass lens A-3, C diaphragm C, B-1 meniscus plastic aspheric lens B-1, B-2 biconvex plastic aspheric lens B-2, and group A front group A, B and group B rear group B.

Detailed Description

In order to make the aforementioned and other features and advantages of the utility model more comprehensible, embodiments accompanied with figures are described in detail below.

As shown in fig. 1 to 6, a 2.8mm large-aperture day and night dual-purpose glass-plastic fixed-focus optical system comprises a biconcave plastic aspheric lens a-1, a meniscus plastic aspheric lens a-2, a biconvex glass lens a-3, a diaphragm C, a meniscus plastic aspheric lens B-1 and a biconvex plastic aspheric lens B-2 which are sequentially arranged at intervals from front to back along an incident light path; the biconcave plastic aspheric lens A-1, the falcate plastic aspheric lens A-2 and the biconvex glass lens A-3 form a front group A with negative focal power, and the falcate plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 form a rear group B with positive focal power.

In this embodiment, the air space between the biconcave plastic aspheric lens a-1 and the meniscus plastic aspheric lens a-2 is 2.36mm, the air space between the meniscus plastic aspheric lens a-2 and the biconvex glass lens a-3 is 1.31mm, the air space between the biconvex glass lens a-3 and the meniscus plastic aspheric lens B-1 is 1.12mm, and the air space between the meniscus plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 is 0.13 mm.

In this embodiment, the focal length of the optical system of the lens is set to f, and the focal lengths of the system shared by the biconcave plastic aspheric lens a-1, the meniscus plastic aspheric lens a-2, the biconvex glass lens a-3, the diaphragm C, the meniscus plastic aspheric lens B-1, and the biconvex plastic aspheric lens B-2 are respectively f1, f2, f3, f4, and f 5; wherein f satisfies the following condition: -6mm < f1< -5 mm; 35mm < f2<37 mm; 7mm < f3<9 mm; -8mm < f4< -6 mm; 5mm < f5<7 mm. Through reasonably distributing the focal power of the optical system according to the proportion, the aberration of the optical system in the wavelength range of 430-850 nm is reasonably corrected and balanced.

In this embodiment, the biconcave plastic aspheric lens A-1, the meniscus plastic aspheric lens A-2, the meniscus plastic aspheric lens B-1, and the biconvex plastic aspheric lens B-2 are made of plastic material.

In this embodiment, a filter D is further disposed on the rear side of the biconvex plastic aspheric lens B-2.

From the above, the front group a has negative power to correct positive power aberration of the rear group B, and the front and rear groups are respectively provided with two high-order aspheric surfaces with complementary powers to correct all high-order aberrations. The whole lens ensures that the refractive index and the focal power of the lens are approximately proportionally distributed, and the balance of the incident angles of the front group of lenses and the rear group of lenses is ensured, so that the sensitivity of an optical system is reduced, and the production possibility is improved. By reasonably distributing the focal lengths of the lenses, the spherical aberration and the field curvature of the imaging system are small at the same time, and the image quality of the axis and the off-axis view field is ensured. Through the optical system formed by the lenses, the total length of the light path is short, and the size of the lens is small; the back focal length is large, and the camera with various interfaces can be matched for use. Wherein, the aspheric surfaces A-1, A-2, B-1 and B-2 are plastic aspheric surfaces, the image quality is good, and the cost is low; the front group A has negative focal power, and the rear group B has positive focal power, so that the lens can still be normally used in high-temperature and low-temperature environments.

In this example, the parameters of each lens are shown in the following table:

the technical indexes of the optical system provided by the embodiment are as follows:

(1) focal length: f =2.8 mm;

(2) relative pore size F = 1.6;

(3) the field angle: 2w is more than or equal to 135 degrees (the image space view field 2 eta' is more than or equal to phi 6 mm);

(4) resolution ratio: can be matched with a CCD or CMOS camera with 800 ten thousand pixels and high resolution;

(5) the total length sigma of the optical path is less than or equal to 23mm, and the optical back intercept L' is more than or equal to 5 mm;

(6) applicable spectral line range: 430 nm-850 nm.

In conclusion, the 2.8mm large-aperture day and night dual-purpose glass-plastic prime optical system provided by the utility model is simple in structure and small in size, realizes high-definition image pickup level at ultralow cost, can still form perfect images in severe environments with different temperatures, and can clearly form images under the condition of low illumination at night.

The above-mentioned preferred embodiments, further illustrating the objects, technical solutions and advantages of the present invention, should be understood that the above-mentioned are only preferred embodiments of the present invention and should not be construed as limiting the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The utility model provides a 2.8mm large aperture, day and night dual-purpose glass-plastic fixed focus optical system which characterized in that: the optical system comprises a biconcave plastic aspheric lens A-1, a meniscus plastic aspheric lens A-2, a biconvex glass lens A-3, a diaphragm C, a meniscus plastic aspheric lens B-1 and a biconvex plastic aspheric lens B-2 which are sequentially arranged at intervals from front to back along an incident light path; the meniscus plastic aspheric lens A-1, the meniscus plastic aspheric lens A-2 and the biconvex glass lens A-3 form a front group A with negative focal power, and the meniscus plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 form a rear group B with positive focal power.

2. The 2.8mm large-aperture, day and night dual-purpose glass-plastic prime optical system of claim 1, wherein: the air interval between the biconcave plastic aspheric lens A-1 and the falcate plastic aspheric lens A-2 is 2.36mm, the air interval between the falcate plastic aspheric lens A-2 and the biconvex glass lens A-3 is 1.31mm, the air interval between the biconvex glass lens A-3 and the falcate plastic aspheric lens B-1 is 1.12mm, and the air interval between the falcate plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 is 0.13 mm.

3. The 2.8mm large-aperture, day and night dual-purpose glass-plastic prime optical system of claim 1, wherein: setting the focal length of an optical system of the lens to be f, and setting the focal lengths of the system shared by the biconcave plastic aspheric lens A-1, the meniscus plastic aspheric lens A-2, the biconvex glass lens A-3, the diaphragm C, the meniscus plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 to be f1, f2, f3, f4 and f5 respectively; wherein f satisfies the following condition: -6mm < f1< -5 mm; 35mm < f2<37 mm; 7mm < f3<9 mm; -8mm < f4< -6 mm; 5mm < f5<7 mm.

4. The 2.8mm large-aperture, day and night dual-purpose glass-plastic prime optical system of claim 1, wherein: the biconcave plastic aspheric lens A-1, the falcate plastic aspheric lens A-2, the falcate plastic aspheric lens B-1 and the biconvex plastic aspheric lens B-2 are made of plastic materials.

5. The 2.8mm large-aperture, day and night dual-purpose glass-plastic prime optical system of claim 1, wherein: the back side of the biconvex plastic aspheric lens B-2 is also provided with a light filter D.