A large aperture all-glass wide-angle fisheye lens and its working method

Abstract

The present invention relates to a large-aperture all-glass wide-angle fisheye lens and a working method thereof, comprising a front group A, a stop C, a rear group B, a parallel plate D and an image plane arranged in sequence from left to right along the incident direction of light, the front group A comprising a first close-contacted group composed of a negative-power meniscus lens A1, a negative-power meniscus lens A2, a negative-power meniscus lens A3 and a positive-power meniscus lens A4 arranged in sequence, and a positive-power biconvex lens A5; the rear group B comprises a second close-contacted group composed of a negative-power biconcave lens B1 and a positive-power biconvex lens B2 arranged in sequence, and a third close-contacted group composed of a positive-power biconvex lens B3, a negative-power meniscus lens B4 and a positive-power biconvex lens B5. The lens has a simple structure, a small size, a field of view of 180°, a large aperture, a high resolution, can shoot a wide range of scenes, and can be used with a 6-8 million pixel CCD or CMOS chip.

Description

Technical field:

[0002] The invention relates to a large-aperture all-glass wide-angle fisheye lens and a working method thereof. Background technology:

[0004] In recent years, as the application scope of camera lenses has become more and more extensive, people have higher and higher requirements for the pixels and field of view of the lens. However, existing lenses generally have the following shortcomings: the field of view is not large enough, often less than 140°, and one or even more lenses need to be installed to capture the required range; the aperture is small, and it cannot meet the minimum imaging illumination requirements of the CCD chip under low illumination and cannot form a clear image; the size is large, and it takes up a lot of space. Summary of the invention:

[0006] The present invention makes improvements on the problems existing in the above-mentioned prior art, that is, the technical problem to be solved by the present invention is to provide a large-aperture all-glass wide-angle fisheye lens and a working method thereof.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: a large-aperture all-glass wide-angle fisheye lens, comprising a front group A, an aperture C, a rear group B, a parallel plate D and an image plane arranged in sequence from left to right along the incident direction of light, the front group A comprises a first closely bonded group consisting of a meniscus lens A1 with negative optical focal length, a meniscus lens A2 with negative optical focal length, a meniscus lens A3 with negative optical focal length and a meniscus lens A4 with positive optical focal length, and a biconvex lens A5 with positive optical focal length; the rear group B comprises a second closely bonded group consisting of a biconcave lens B1 with negative optical focal length and a biconvex lens B2 with positive optical focal length, and a third closely bonded group consisting of a biconvex lens B3 with positive optical focal length, a meniscus lens B4 with negative optical focal length and a biconvex lens B5 with positive optical focal length.

[0008] Furthermore, the air gap between the meniscus lens A1 and the meniscus lens A2 is 2.66mm-2.67mm, the air gap between the meniscus lens A2 and the meniscus lens A3 is 4.83mm-4.84mm, the air gap between the meniscus lens A4 and the biconvex lens A5 is 0.1mm-0.11mm; the air gap between the biconvex lens B2 and the biconvex lens B3 is 0.14mm-0.15mm, the air gap between the biconvex lens B3 and the meniscus lens B4 is 0.12mm-0.13mm, and the air gap between the biconvex lens B5 and the parallel plate D is 0.1mm.

[0009] Furthermore, the total focal length of the optical system is set to f, and along the incident direction of light, the focal lengths of the first close-contacted group consisting of meniscus lens A1, meniscus lens A2, meniscus lens A3 and meniscus lens A4, the second close-contacted group consisting of biconvex lens A5, biconcave lens B1 and biconvex lens B2, and the third close-contacted group consisting of biconvex lens B3, meniscus lens B4 and biconvex lens B5 are set to f1, f2, f3, f4, f5, f6, f7 in sequence, and the relationship between the focal lengths of the lenses is as follows: -9.5 <f1 / f<-9、-7<f2 / f<-6.5、95<f3 / f<100、11<f4 / f<11.5、-23<f5 / f<-22.5、8.5<f6 / f<9、24<f7 / f<24.5。

[0010] Another technical solution adopted by the present invention is: a working method of a large-aperture all-glass wide-angle fisheye lens. During operation: when light is incident, the light path sequentially enters the front group A, the aperture C, the rear group B, and the parallel plate D, and finally forms an image on the image plane. When the light passes through the front group A, the five lenses of the front group A can converge the incident angle of the light. When the light passes through the rear group B, the five lenses of the rear group B can balance the aberrations. When the light passes through the closely bonded group of the rear group B, the secondary spectrum and spherical aberration can be corrected.

[0011] Compared with the prior art, the present invention has the following effects: the lens has a simple structure, a small size, a field of view of 180°, a large aperture, a high resolution, can capture a wide range of scenes, and can be used with a 6-8 megapixel CCD or CMOS chip. Description of the drawings:

[0013] Figure 1 is a schematic structural diagram of an optical system according to an embodiment of the present invention;

[0014] Figure 2 is a schematic diagram of the MTF value of visible light in an embodiment of the present invention;

[0015] Figure 3 Schematic diagram of field curvature and F-Theta distortion in an embodiment of the present invention.

[0016] In the figure:

[0017] A-front group A; A1-meniscus lens A1; A2-meniscus lens A2; A3-meniscus lens A3; A4-meniscus lens A4; A5-biconvex lens A5; B-rear group B; B1-biconcave lens B1; B2-biconvex lens B2; B3-biconvex lens B3; B4-meniscus lens B4; B5-biconvex lens B5; C-aperture; D-parallel plate. Specific implementation method:

[0019] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0021] like Figures 1 to 3 As shown, a large-aperture all-glass wide-angle fisheye lens of the present invention comprises a front group A, an aperture C, a rear group B, a parallel plate D and an IMA image plane which are sequentially arranged from left to right along the incident direction of light, wherein the front group A comprises a first closely bonded group consisting of a meniscus lens A1 with negative optical power, a meniscus lens A2 with negative optical power, a meniscus lens A3 with negative optical power and a meniscus lens A4 with positive optical power, and a biconvex lens A5 with positive optical power; the rear group B comprises a second closely bonded group consisting of a biconcave lens B1 with negative optical power and a biconvex lens B2 with positive optical power, and a third closely bonded group consisting of a biconvex lens B3 with positive optical power, a meniscus lens B4 with negative optical power and a biconvex lens B5 with positive optical power.

[0022] In this embodiment, the air gap between the meniscus lens A1 and the meniscus lens A2 is 2.66mm-2.67mm, the air gap between the meniscus lens A2 and the meniscus lens A3 is 4.83mm-4.84mm, and the air gap between the meniscus lens A4 and the biconvex lens A5 is 0.1mm-0.11mm; the air gap between the biconvex lens B2 and the biconvex lens B3 is 0.14mm-0.15mm, the air gap between the biconvex lens B3 and the meniscus lens B4 is 0.12mm-0.13mm, and the air gap between the biconvex lens B5 and the parallel plate D is 0.1mm.

[0023] In this embodiment, the total focal length of the optical system is set to f, and along the incident direction of light, the focal lengths of the first close-contacted group consisting of meniscus lens A1, meniscus lens A2, meniscus lens A3 and meniscus lens A4, the second close-contacted group consisting of biconvex lens A5, biconcave lens B1 and biconvex lens B2, and the third close-contacted group consisting of biconvex lens B3, meniscus lens B4 and biconvex lens B5 are set to f1, f2, f3, f4, f5, f6, and f7 in sequence. The relationship between the focal lengths of the lenses is as follows: -9.5 <f1 / f<-9、-7<f2 / f<-6.5、95<f3 / f<100、11<f4 / f<11.5、-23<f5 / f<-22.5、8.5<f6 / f<9、24<f7 / f<24.5。

[0024] In this embodiment, specific parameters of each lens are shown in Table 1 below.

[0025]

[0026] Table 1

[0027] In this embodiment, the technical indicators achieved by this optical system are as follows: (1) focal length: EFFL = 2 mm; (2) F number = 2.0; (3) field of view: 2w ≥ 180°; (4) imaging circle diameter is greater than Φ6.6; (5) working spectrum range: 430 nm ~ 730 nm; (6) total optical length TTL ≤ 32.5 mm, optical back intercept ≥ 4 mm; (7) F-Theta distortion = -9%; (8) This lens is suitable for 6-8 million pixel high-resolution CCD or CMOS cameras.

[0028] In this embodiment, when the lens is working: when light is incident, the light path sequentially enters the front group A, the aperture C, the rear group B, and the parallel plate, and finally forms an image on the IMA image plane. When the light passes through the front group A, the five lenses of the front group A can converge the incident angle of the light. When the light passes through the rear group B, the five lenses of the rear group B can balance the aberrations. The biconvex lens A5 in the front group A is made of glass with a low refractive index and a high Abbe number, the biconcave lens B1 in the rear group B is made of glass with a high refractive index and a low Abbe number, and the meniscus lens B4 is made of glass with a high refractive index and a low Abbe number. When the light passes through the closely bonded lens group of the rear group B, the secondary spectrum and spherical aberration can be corrected, so that the lens system can obtain good correction of chromatic aberration through reasonable matching of materials.

[0029] When designing the lens, the visible spectrum of F, C, and D is used, and the F / # is set to 2. The aperture is large, and the image can be quickly and clearly formed even in low illumination. By reasonably allocating the focal length of 10 lenses, the total optical length of the lens is compressed while maintaining small distortion, making the optical system compact and helping to save cost.

[0030] This lens adopts a ten-piece structure, which reasonably distributes the optical power. The first five lenses converge the incident angle of light, and the last five lenses balance the aberration. The biconvex lens A5 in the front group A adopts glass with low refractive index and high Abbe number, the biconcave lens B1 in the second close-contact cemented group adopts glass with high refractive index and low Abbe number, and the meniscus lens B4 adopts glass with high refractive index and low Abbe number. When light passes through the lens, it can correct the secondary spectrum and spherical aberration, so that the lens system can get good correction of chromatic aberration through reasonable matching of materials.

[0031] If the present invention discloses or involves components or structures that are fixedly connected to each other, then, unless otherwise stated, the fixed connection can be understood as: a detachable fixed connection (for example, connection using bolts or screws), and can also be understood as: a non-detachable fixed connection (for example, riveting, welding). Of course, the mutual fixed connection can also be replaced by an integrated structure (for example, manufactured by integrated molding using a casting process) (except when it is obviously impossible to use an integrated molding process).

[0032] In addition, unless otherwise stated, the terms used to indicate positional relationships or shapes in any of the technical solutions disclosed in the present invention include states or shapes that are approximate, similar, or close to them.

[0033] Any component provided by the present invention may be assembled from a plurality of separate components, or may be a separate component manufactured by an integral forming process.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. A large aperture all-glass wide-angle fisheye lens, characterized in that: It comprises a front group A, an aperture C, a rear group B, a parallel plate D and an image plane which are arranged in sequence from left to right along the incident direction of light, wherein the front group A is composed of a first closely bonded group consisting of a meniscus lens A1 with negative focal power, a meniscus lens A2 with negative focal power, a meniscus lens A3 with negative focal power and a meniscus lens A4 with positive focal power which are arranged in sequence, and a biconvex lens A5 with positive focal power; the rear group B is composed of a second closely bonded group consisting of a biconcave lens B1 with negative focal power and a biconvex lens B2 with positive focal power which are arranged in sequence, and a third closely bonded group consisting of a biconvex lens B3 with positive focal power, a meniscus lens B4 with negative focal power and a biconvex lens B5 with positive focal power which are arranged in sequence; The air gap between the meniscus lens A1 and the meniscus lens A2 is 2.66mm-2.67mm, the air gap between the meniscus lens A2 and the meniscus lens A3 is 4.83mm-4.84mm, the air gap between the meniscus lens A4 and the biconvex lens A5 is 0.1mm-0.11mm; the air gap between the biconvex lens B2 and the biconvex lens B3 is 0.14mm-0.15mm, the air gap between the biconvex lens B3 and the meniscus lens B4 is 0.12mm-0.13mm, and the air gap between the biconvex lens B5 and the parallel plate D is 0.1mm; The total focal length of the optical system is set to f, and along the incident direction of light, the focal lengths of the first close-contacted group consisting of meniscus lens A1, meniscus lens A2, meniscus lens A3 and meniscus lens A4, the second close-contacted group consisting of biconvex lens A5, biconcave lens B1 and biconvex lens B2, and the third close-contacted group consisting of biconvex lens B3, meniscus lens B4 and biconvex lens B5 are set to f1, f2, f3, f4, f5, f6, f7 in sequence. The relationship between the focal lengths of the lenses is as follows: -9.5 <f1 / f<-9、-7<f2 / f<-6.5、95<f3 / f<100、11<f4 / f<11.5、-23<f5 / f<-22.5、8.5<f6 / f<9、24<f7 / f<24.5。 2. A method for operating a large aperture all-glass wide-angle fisheye lens, characterized in that: The invention comprises a large-aperture all-glass wide-angle fisheye lens as claimed in claim 1, wherein when the light is incident, the light path sequentially enters the front group A, the aperture C, the rear group B, and the parallel plate D, and finally forms an image on the image plane; when the light passes through the front group A, the five lenses of the front group A can converge the incident angle of the light; when the light passes through the rear group B, the five lenses of the rear group B can balance the aberration; when the light passes through the closely bonded group of the rear group B, the secondary spectrum and spherical aberration can be corrected.

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