CN115437112A - Large-aperture panoramic optical imaging system - Google Patents

Abstract

The invention relates to a large-aperture panoramic optical imaging system, which sequentially includes a mirror, a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, and a sixth lens from the object side to the image side , the seventh lens and the eighth lens; the aperture stop is located between the third lens and the fourth lens, and the fourth lens and the fifth lens are cemented to form a doublet lens; the optical surface of the mirror and the first The optical surfaces of the eight lenses facing the image side are aspherical surfaces, and the optical surfaces of the other lenses are all spherical surfaces. This type of catadioptric panoramic optical imaging system has the characteristics of large aperture, wide field of view, good image uniformity, good imaging quality, relatively simple structure, easy processing and easy installation.

Description

A large-aperture panoramic optical imaging system

technical field

The invention relates to panoramic optical imaging technology in the photoelectric industry, in particular to a large-aperture catadioptric panoramic optical imaging system.

Background technique

With the rapid development of modern science and technology, the fisheye lens system has a large field of view imaging that cannot be achieved by conventional optical systems, making it widely used in robot navigation, scene monitoring, and target recognition. The aberration of this type of optical system is often relatively large, especially in the case of large-aperture imaging, so this type of system requires one or more negative meniscus lenses and multiple refractive lenses to compress the field of view and correct aberrations. However, a catadioptric imaging system is often composed of a mirror and a set of refractive lenses, which will greatly reduce the complexity of the system structure, making it more and more common in various fields. This type of catadioptric panoramic optical imaging system uses a reflector to collect and compress the incident light in the horizontal direction, and transfers it to a set of refracting lens groups behind, so as to realize real-time acquisition of 360° in the horizontal direction and vertical direction. A panoramic image from a certain angle.

Contents of the invention

The technical problem to be solved in the present invention is to solve the problem of complex structure and poor imaging performance in the current panoramic imaging system, and proposes to design a large-aperture catadioptric panoramic optical imaging using a mirror and a group of refractive lenses. system. For the catadioptric panoramic imaging system, although its optical elements are arranged axisymmetrically, the light hits the surface of the optical element at a large incident angle, which causes it to be inconsistent with the imaging characteristics of the paraxial optical system, and has a plane symmetric optical system imaging performance, so that the Seidel aberration analysis method cannot guide the design of such systems. Therefore, the present invention analyzes the aberrations of the catadioptric panoramic imaging system based on the sixth-order wave aberration theory of the ultra-large field of view optical system, and establishes a system image quality evaluation function to correct such system aberrations, thereby obtaining better imaging quality The system provides a means for system aberration optimization. This type of catadioptric panoramic optical imaging system has the characteristics of large aperture, wide field of view, good image uniformity, good imaging quality, relatively simple structure, easy processing and easy installation.

The present invention adopts the following technical solutions: a large-aperture panoramic optical imaging system, which sequentially includes a mirror, a first lens, a second lens, a third lens, an aperture stop, a fourth lens, a fifth lens, the sixth lens, the seventh lens and the eighth lens; the aperture stop is located between the third lens and the fourth lens, and the fourth lens and the fifth lens are cemented to form a doublet lens; the reflection The mirror optical surface and the optical surface facing the image side of the eighth lens are aspheric, and the optical surfaces of the other lenses are all spherical.

Preferably, the full field of view of the optical system is 120°, the total focal length is 0.33mm, the F number is 2.6, the total length is 128.96mm, the detection wavelength range is 400nm-700nm, and the dominant wavelength is 586.7nm.

Preferably, the aspherical surface coefficients of the optical surface of the reflector and the optical surface of the eighth lens facing the image side satisfy the quadratic conic surface equation: x ² +y ² =a ₁ z+a ₂ z ²

In the above formula, the parameters x, y, z are the coordinates of any point on the optical surface, a ₁ =2R ₀ , R ₀ represents the radius of curvature at the apex of the aspheric surface curve of the optical surface of the mirror or lens, a ₂ is the surface coefficient of the optical surface, where a ₂ ≠-1.

Preferably, the surface coefficients of the optical surface of the reflector and the optical surface of the eighth lens facing the image side are 1.88 and -65.25, respectively.

Preferably, the first lens, the second lens and the third lens have the same refractive index.

Preferably, the refractive index of the fourth lens is the smallest among all the lenses.

Preferably, the distance between the first lens and the reflective mirror is the maximum value of the distances of all adjacent optical structures.

The present invention has the following beneficial effects: In the present invention, the reflector M1 is used to collect and compress the incident light in the horizontal direction, so as to achieve the effect of compressing the field of view of the object, so that the field of view of the light after passing through the reflector M1 It can be received by the refracting lens group, thereby ensuring the imaging system's requirements for large field of view and large aperture shooting. The types of lenses used in the imaging system are less, which makes the processing cost of the imaging system low and easy to install during the design process. In addition, in the imaging system, the optical surface of the mirror M1 and the optical surface of the eighth refracting lens L8 facing the image side are designed aspherically, which effectively corrects the image existing in the system with a large aperture and a large field of view. Difference. This type of catadioptric panoramic optical imaging system has the characteristics of large aperture, wide field of view, good image uniformity, good imaging quality, relatively simple structure, easy processing and easy installation.

Description of drawings

In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore do not It should be regarded as a limitation on the scope, and those skilled in the art can also obtain other related drawings based on these drawings without creative work.

Fig. 1 is a schematic diagram of the optical structure of the present invention;

Fig. 2 is a modulation transfer function (MTF) curve diagram of the present invention;

Fig. 3 is the relative illuminance figure of the present invention;

Fig. 4 is an optical path diagram of the present invention.

In the figure: 1-mirror; 2-first lens; 3-second lens; 4-third lens; 5-aperture stop; 6-fourth lens; 7-fifth lens; 8-sixth lens; 9-seventh lens; 10-eighth lens.

detailed description

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments It is some embodiments of the present invention, but not all of them. Based on the implementation manners in the present invention, all other implementation manners obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the invention. Based on the implementation manners in the present invention, all other implementation manners obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Orientation indicated by rear, left, right, vertical, horizontal, top, bottom, inside, outside, clockwise, counterclockwise, etc. The positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as limiting the invention.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

In the present invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection" and "fixation" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection , or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention according to specific situations.

In the present invention, unless otherwise clearly specified and limited, a first feature being "on" or "under" a second feature may include direct contact between the first and second features, and may also include the first and second features Not in direct contact but through another characteristic contact between them. Moreover, "above", "above" and "above" the first feature on the second feature include that the first feature is directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. "Below", "under" and "under" the first feature to the second feature include that the first feature is directly below and obliquely below the second feature, or simply means that the first feature is less horizontally than the second feature.

Example

The following are only preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the following examples, and all technical solutions under the idea of the present invention belong to the scope of protection of the present invention.

Referring to accompanying drawing 1 of the specification, a large-aperture panoramic optical imaging system, along the light propagation direction from the object side to the image side, sequentially includes a mirror 1, a first lens 2, a second lens 3, a third lens 4, an aperture light Stop 5, fourth lens 6, fifth lens 7, sixth lens 8, seventh lens 9 and eighth lens 10. The aperture stop is located between the third lens 4 and the fourth lens 6, and the fourth lens 6 and the fifth lens 7 form a doublet lens. The optical surface of the reflector 1 and the optical surface facing the image side of the eighth lens 10 adopt an aspheric design, and the optical surfaces of the other lenses adopt a spherical design. The large-aperture panoramic optical imaging system has a full field of view of 120°, a total focal length of 0.33mm, an F number of 2.6, and a total length of 128.96mm. The detectable wavelength range is 400nm-700nm, and the dominant wavelength is 586.7nm.

The materials of the reflector 1, the first lens 2, the second lens 3, the third lens 4, the fourth lens 6, the fifth lens 7, the sixth lens 8, the seventh lens 9 and the eighth lens 10 are MIRROR (n=1.0000), N-PSK53A(n=1.6180), N-PSK53A(n=1.6180), N-PSK53A(n=1.6180), BK7(n=1.5168), PSK52(n=1.6031), PSK54(n =1.5860), PSK54 (n=1.5860) and PSK54 (n=1.5860); where n is the refractive index.

The aspheric surface coefficient of the optical surface of the reflector or lens satisfies the quadratic conic surface equation:

x ² +y ² =a ₁ z+a ₂ z ² ;

In the above formula, the parameters x, y, z are the coordinates of any point on the optical surface, a ₁ =2R ₀ , R ₀ represents the radius of curvature at the apex of the aspheric surface curve of the optical surface of the mirror or lens, a ₂ is the coefficient that determines the optical surface type; when a ₂ ≠ -1, the optical surface is aspheric, and the specific classification is as follows:

When a ₂ <-1, -1<a ₂ <0, a ₂ =0 and a ₂ >0, the surface types of the optical surface are oblate ellipse, long ellipse, paraboloid and hyperboloid; if a ₂ = -1, the optical surface is spherical.

The surface coefficients of the optical surface of the reflector 1 and the image-side optical surface of the eighth lens 10 are 1.88 and -65.25 respectively, and the surface coefficients of the optical surfaces of the other refracting lenses are -1.

The optical surface of the reflector 1 and the optical surface of the eighth lens 10 towards the image side all adopt an aspheric design, and the fourth lens 6 and the fifth lens 7 form a doublet lens, which correct the aberration of the lens played a very important role.

Fig. 2 and Fig. 3 are respectively a modulation transfer function (MTF) curve and a relative illuminance diagram of a large-aperture panoramic optical imaging system. From Figure 2, it can be seen that the imaging quality of the catadioptric panoramic imaging system is very high; from Figure 3, it can be seen that the relative illuminance of the catadioptric panoramic imaging system is very high, which meets the design requirements.

The structural parameters of a large-aperture panoramic optical imaging system described in this embodiment are shown in Table 1 (the direction is from the object side to the image side along the light propagation direction):

Table 1 Optical structural parameters of a large-aperture panoramic optical imaging system

In the above table, from the object plane to the image plane, along the incident direction of the light, S1 is the optical surface of the mirror 1; S2 and S3 are the optical surfaces of the first lens 2 facing the object side and the image side; S4 and S5 are the second lenses 3 towards the object side and the image side optical surface; S6 and S7 are the third lens 4 towards the object side and the image side optical surface; S8 and S9 are the fourth lens 6 towards the object side and the image side optical surface; S9 and S10 is the optical surface of the fifth lens 7 towards the object side and the image side; S11 and S12 are the optical surfaces of the sixth lens 8 towards the object side and the image side; S13 and S14 are the optical surfaces of the seventh lens 9 towards the object side and the image side ; S15 and S16 are the optical surfaces of the eighth lens 10 facing the object side and the image side. Wherein, the fourth lens 6 and the fifth lens 7 form a doublet lens, so S9 is the cemented optical surface of the fourth lens 6 and the fifth lens 7 . It can be seen from the above table that the distance between the first lens 2 and the reflector 1 is the farthest in each optical structure, and the distance between the optical surface S2 facing the object side and the reflector 1 is 50.12mm. The first lens 2, second lens 3, and third lens 4 close to the object side have the same refractive index and have the highest refractive index, while the fourth lens 6 on the side of the aperture stop has the smallest refractive index among all lenses .

To sum up, with the help of the above-mentioned technical solution of the invention, the catadioptric panoramic optical imaging system can be made to have large aperture, wide field of view, good image uniformity, good imaging quality, relatively simple structure, easy processing and easy installation. features.

Claims (7)

1. A large-aperture panoramic optical imaging system is characterized by comprising a reflector, a first lens, a second lens, a third lens, an aperture diaphragm, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens from an object space to an image space in sequence; the aperture diaphragm is positioned between the third lens and the fourth lens, and the fourth lens and the fifth lens are glued to form a double-cemented lens; the optical surfaces of the reflector and the eighth lens facing the image space are aspheric surfaces, and the optical surfaces of the rest lenses are spherical surfaces.

2. The large aperture panoramic optical imaging system of claim 1, wherein the optical system has a full field angle of 120 °, a total focal length of 0.33mm, an f-number of 2.6, a total length of 128.96mm, a probe wavelength range of 400nm to 700nm, and a dominant wavelength of 586.7nm.

3. The large-aperture panoramic optical imaging system according to claim 1, wherein aspheric surface coefficients of the optical surfaces of the reflector and the eighth lens facing the image side satisfy a conic equation: x is the number of ² +y ² ＝a ₁ z+a ₂ z ²

In the above formula, the parameters x, y, z are coordinates of an arbitrary point on the optical surface, a ₁ ＝2R ₀ ，R ₀ Denotes the radius of curvature at the apex of the aspherical profile curve of the optical surface of the mirror or lens, a ₂ Is the surface form factor of the optical surface, wherein a ₂ ≠-1。

4. The large-aperture panoramic optical imaging system of claim 3, wherein the surface type coefficients of the optical surface of the reflector and the optical surface of the eighth lens facing the image side are 1.88 and-65.25, respectively.

5. The large aperture panoramic optical imaging system of claim 1, wherein the first, second and third lenses have the same refractive index.

6. The large aperture panoramic optical imaging system of claim 1, wherein the refractive index of the fourth lens is the smallest of all lenses.

7. The large aperture panoramic optical imaging system of claim 1, wherein the distance between the first lens and the mirror is the maximum of all adjacent optical structure distances.

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