High-definition fisheye optical system

Abstract

The utility model discloses a high-definition fisheye optical system, and relates to the technical field of optical imaging. The optical system sequentially comprises nine lenses from the object side to the image side along the optical axis. Wherein the first lens, the second lens, the fifth lens and the seventh lens are meniscus lenses, and the fourth lens, the sixth lens, the eighth lens and the ninth lens are biconvex lenses; the third lens is a biconcave lens; the sixth lens and the seventh lens are combined into a balsaming lens; the first lens, the second lens, the third lens, and the fourth lens are stacked in a lens-on-lens manner. According to the high-definition fisheye optical system provided by the utility model, the combination of nine optical lenses is designed, and the first four optical lenses are directly stacked in a manner that the lenses are close to the lenses, so that the imaging effects of large image surface, ultra-wide angle, high definition and good infrared confocal are realized while the total optical length is short.

Description

TECHNICAL FIELD

[0001] The utility model relates to optical imaging technical field, concretely relates to a kind of high-definition fisheye optical system. BACKGROUND

[0002] Fisheye lens is a special type of photographic lens, it has super large field of view, so it is widely used in scene monitoring, satellite positioning, robot navigation, micro intelligent system and engineering surveying and mapping etc.

[0003] In order to obtain better imaging effect, in some designs, fisheye lens can be combined by a dozen different lenses. These lenses are refracted to different degrees in the imaging process, and projected onto the imaging plane with limited size. However, this will cause the optical total length to be longer, affecting the miniaturization application of fisheye lens. SUMMARY

[0004] The technical problem to be solved by the utility model is to provide a kind of high-definition fisheye optical system, the combination of nine optical lenses is designed, and the first four are directly stacked in lens-to-lens mode, achieving large image plane, super wide angle, high definition and good infrared confocal imaging effect while shortening the optical total length.

[0005] The utility model is realized as follows:

[0006] A kind of high-definition fisheye optical system, first lens, second lens, third lens, fourth lens, fifth lens, sixth lens, seventh lens, eighth lens and ninth lens are sequentially included along optical axis from object side to image side;Wherein, first lens, second lens, fifth lens and seventh lens are crescent-shaped lenses, fourth lens, sixth lens, eighth lens and ninth lens are double convex lenses;Third lens is double concave lens;Sixth lens and seventh lens are combined into cemented lens;First lens, second lens, third lens, fourth lens are stacked in lens-to-lens mode.

[0007] Further, the refractive index of the first lens is 1.74, the refractive index of the second lens is 1.74, the refractive index of the fourth lens is 1.92, and the refractive index of the cemented lens is 1.76.

[0008] Further, the optical total length of the optical system is 29mm.

[0009] Further, the centering coefficient of the first lens is 0.16, the centering coefficient of the second lens is 0.13, the centering coefficient of the fifth lens is 0.12, and the centering coefficient of the seventh lens is 0.26.

[0010] Further, the third lens, the fifth lens, the eighth lens and the ninth lens are made of the same low-dispersion optical material, and the optical Abbe number is 95.1.

[0011] Further, a diaphragm is further included, and the diaphragm is arranged between the fourth lens and the fifth lens; the first lens, the second lens and the third lens before the diaphragm are negative focal lengths, the fourth lens is a positive focal length, and the fifth lens, the cemented lens, the eighth lens and the ninth lens after the diaphragm are positive focal lengths.

[0012] Further, the diaphragm is realized by a spacer ring arranged between the fourth lens and the fifth lens.

[0013] Further, a protective window sheet is further included and arranged between the ninth lens and an imaging surface.

[0014] Further, the sixth lens and the seventh lens are optical cement.

[0015] Further, the radii of curvature of the nine optical spherical lenses satisfy the following conditions:

[0016] The first lens: 15≤R1≤23, 5.0≤R2≤10.0;

[0017] The second lens: 7≤R1≤16, 3.0≤R2≤8.0;

[0018] The third lens: -20≤R1≤-13, 3.0≤R2≤7.0;

[0019] The fourth lens: 7≤R1≤13, -30≤R2≤-23;

[0020] The fifth lens: -12≤R1≤-5, -8.0≤R2≤-3.5;

[0021] The sixth lens: 19≤R1≤30, -10.0≤R2≤-2.0;

[0022] The seventh lens: -10.0≤R1≤-2.0, -21≤R2≤-10;

[0023] The eighth lens: 15≤R1≤24, -15.0≤R2≤-5.0;

[0024] The ninth lens: 8≤R1≤15, -60≤R2≤-48;

[0025] Wherein, R1 is the object side curvature, and R2 is the image side curvature.

[0026] The technical scheme of the utility model at least has the following advantages:

[0027] By setting the combination of nine lenses, and combining the sixth lens and the seventh lens as a cemented lens, the first lens, the second lens, the third lens and the fourth lens are stacked in a lens-by-lens manner, thereby effectively reducing the total optical length; the light beam is first limited to the aperture range of the diaphragm by the three negative focal length and one positive focal length lenses in front of the diaphragm, and then the 7MM image surface and high-definition image quality are realized by reasonable distribution of the four positive focal length lenses behind the diaphragm, so that the whole fisheye optical system has the advantages of short total length, large image surface, ultra-wide angle and good imaging quality. BRIEF DESCRIPTION OF DRAWINGS

[0028] The utility model will be further described below with reference to the drawings and embodiments.

[0029] Figure 1 It is a structural schematic view of the embodiment of the utility model;

[0030] Figure 2 It is a point column diagram schematic view of the embodiment of the utility model;

[0031] Figure 3 It is an optical system field curvature and distortion schematic view of the embodiment of the utility model;

[0032] Figure 4 It is an optical power chromatic aberration schematic view of the embodiment of the utility model;

[0033] Figure 5 It is an MTF curve schematic view of the embodiment of the utility model;

[0034] Figure 6 It is a light ray light fan diagram of the embodiment of the utility model. DETAILED DESCRIPTION

[0035] The technical scheme of the utility model will be clearly and completely described below in combination with the drawings and specific embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without making creative labor belong to the protection scope of the utility model.

[0036] In the description of the utility model, it needs to be explained that the orientation or position relation indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like is the orientation or position relation based on the drawing shown, and is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the indicated device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it cannot be understood as the limitation of the utility model.

[0037] Please refer to Figure 1As shown, the embodiment provides a high-definition fisheye optical system, which comprises, in order from the object side to the image side along the optical axis, a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, and a ninth lens 9; wherein the first lens 1, the second lens 2, the fifth lens 5, and the seventh lens 7 are meniscus lenses, the fourth lens 4, the sixth lens 6, the eighth lens 8, and the ninth lens 9 are double convex lenses; the third lens 3 is a double concave lens; the sixth lens 6 and the seventh lens 7 are combined into a cemented lens; and the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4 are stacked in a lens-to-lens manner. By setting the combination of nine lenses, and simultaneously combining the sixth lens 6 and the seventh lens 7 into a cemented lens, and stacking the first lens 1, the second lens 2, the third lens 3, and the fourth lens 4 in a lens-to-lens manner, the total optical length is effectively reduced.

[0038] Preferably, the refractive index of the first lens 1 is 1.74, the refractive index of the second lens 2 is 1.74, the refractive index of the fourth lens 4 is 1.92, and the refractive index of the cemented lens is 1.76. By using high-refractive-index glass to change the light path to increase the field of view and shorten the total length. The total optical length of the optical system of the embodiment is 29 mm.

[0039] In a possible implementation, the radii of curvature of the nine optical spherical lenses satisfy the following conditions:

[0040] The first lens 1: 15≤R1≤23, 5.0≤R2≤10.0;

[0041] The second lens 2: 7≤R1≤16, 3.0≤R2≤8.0;

[0042] The third lens 3: -20≤R1≤-13, 3.0≤R2≤7.0;

[0043] The fourth lens 4: 7≤R1≤13, -30≤R2≤-23;

[0044] The fifth lens 5: -12≤R1≤-5, -8.0≤R2≤-3.5;

[0045] The sixth lens 6: 19≤R1≤30, -10.0≤R2≤-2.0;

[0046] The seventh lens 7: -10.0≤R1≤-2.0, -21≤R2≤-10;

[0047] The eighth lens 8: 15≤R1≤24, -15.0≤R2≤-5.0;

[0048] The ninth lens 9: 8≤R1≤15, -60≤R2≤-48;

[0049] Wherein, R1 is the object side curvature, R2 is the image side curvature.

[0050] Each lenticular lens and biconcave lens two spherical surface curvature is obvious, convenient processing and assembly. At the same time, the crescent type lens in processing involves a centering coefficient, the coefficient is too small will not help processing, and then seriously affect the system optical imaging quality, it is necessary to briefly explain below. The centering coefficient formula is as follows:

[0051]

[0052] Wherein D1, D2 is the outer diameter of the fixture or the diameter of the lens on both sides, R1, R2 is the radius of curvature of the two surfaces; when both surfaces are positive or negative (lenticular or biconcave lens), the formula selects the positive sign (+); when one positive and one negative (crescent lens), the formula selects the negative sign (-), according to the calculation result, can be classified as follows:

[0053] Z < 0.05, centering is difficult;

[0054] 0.05 ≤ Z ≤ 0.15, normal centering

[0055] Z > 0.15, centering is easy.

[0056] Preferably, the centering coefficient of the first lens 1 is 0.16, the centering coefficient of the second lens 2 is 0.13, the centering coefficient of the fifth lens 5 is 0.12, and the centering coefficient of the seventh lens 7 is 0.26. Therefore, the four crescent lenses are easy to process and will not cause large eccentricity.

[0057] Preferably, the third lens 3, the fifth lens 5, the eighth lens 8 and the ninth lens 9 adopt the same low dispersion optical material, and the optical Abbe number is 95.1. Using four lenses with low refractive index and low dispersion coefficient can reduce infrared defocus and achieve better infrared confocal imaging and reduce chromatic aberration. At the same time, the four lenses are made of the same material, which can be coated at the same time, greatly saving the cost.

[0058] Preferably, it further comprises a diaphragm 10, and the diaphragm 10 is arranged between the fourth lens 4 and the fifth lens 5; the diaphragm 10 is arranged at a position behind the fourth lens 4, used for limiting the size of the light beam of the system, ensuring that the optical aberration is kept within a certain range, which can effectively improve the optical imaging quality. The first lens 1, the second lens 2 and the third lens 3 in front of the diaphragm 10 are negative focal power, the fourth lens 4 is positive focal power, and the fifth lens 5, the cemented lens, the eighth lens 8 and the ninth lens 9 behind the diaphragm 10 are all positive focal power.

[0059] In a possible implementation manner, the diaphragm 10 is realized by a spacer ring arranged between the fourth lens 4 and the fifth lens 5.

[0060] Preferably, a protective window sheet 11 is further included and arranged between the ninth lens 9 and the imaging plane.

[0061] Preferably, the sixth lens 6 and the seventh lens 7 are positioned by optical cementing.

[0062] In the embodiment, the optical system composed of the above lenses achieves the following optical indexes:

[0063] By reasonable distribution of the three negative focal length lenses and one positive focal length lens in front of the diaphragm and the four positive focal length lenses behind the diaphragm, the effect of wide angle and large field of view can be achieved, the field of view angle can reach 185° with a 7mm imaging plane (CCD & CMOS), the total optical length is only 29mm, and the pixels can meet the effect of 12MP.

[0064] Figure 2 The point array diagram is a schematic diagram of the point array diagram of the embodiment of the utility model, and the point array diagram is basically within the Airy disk range, which indicates that the imaging light is relatively concentrated and the imaging quality is high.

[0065] Figure 3 The optical system field curvature and distortion diagram is a schematic diagram of the optical system field curvature and distortion of the embodiment of the utility model; the fisheye lens has distortion, but the distortion of the optical system can be controlled within -97.5%.

[0066] Figure 4 The optical magnification chromatic aberration diagram is a schematic diagram of the optical magnification chromatic aberration of the embodiment of the utility model; the curve fitting degree is relatively high, which indicates that the system chromatic aberration is small.

[0067] Figure 5 The MTF curve diagram is a schematic diagram of the MTF curve of the embodiment of the utility model, and the system MTF value is basically above 0.2 at a frequency of 300, which indicates that the overall imaging quality of the system is high.

[0068] Figure 6 The light ray fan diagram is a schematic diagram of the light ray fan diagram of the embodiment of the utility model, and it can be seen that the defocus is small, which indicates that the infrared confocal is good.

[0069] The utility model discloses a combination of nine lenses, and the sixth lens and the seventh lens are combined as cemented lenses, and the first lens, the second lens, the third lens and the fourth lens are stacked in a lens-by-lens manner, thereby effectively reducing the total optical length; the light beam is first limited to the aperture range of the diaphragm by the three negative focal length lenses and one positive focal length lens in front of the diaphragm, and then the reasonable distribution of the four positive focal length lenses behind the diaphragm is utilized to realize a 7mm imaging plane and high-definition image quality, so that the fisheye optical system has the advantages of short total length, large imaging plane, ultra-wide angle, high imaging quality, significantly reduced visual distortion, enhanced overall clarity, flexible configuration, rapid response to changes, durability and easy maintenance.

[0070] Although the specific embodiments of the present application are described above, those skilled in the art should understand that the specific embodiments described by us are only illustrative, not for limiting the scope of the present application, and equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present application should be covered within the scope of the claims of the present application.

Claims

1. A high definition fisheye optical system characterized by: The optical system comprises, in order from the object side to the image side along the optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens; wherein the first lens, the second lens, the fifth lens, and the seventh lens are meniscus lenses, the fourth lens, the sixth lens, the eighth lens, and the ninth lens are double convex lenses; the third lens is a double concave lens; the sixth lens and the seventh lens are combined into a cemented lens; and the first lens, the second lens, the third lens, and the fourth lens are stacked in a lens-by-lens manner.

2. The optical system of claim 1, wherein: The refractive index of the first lens is 1.74, the refractive index of the second lens is 1.74, the refractive index of the fourth lens is 1.92, and the refractive index of the cemented lens is 1.

76.

3. The optical system of claim 2, wherein: The total optical length of the optical system is 29 mm.

4. The optical system of claim 1, wherein: The centering coefficient of the first lens is 0.16, the centering coefficient of the second lens is 0.13, the centering coefficient of the fifth lens is 0.12, and the centering coefficient of the seventh lens is 0.

26.

5. The optical system of claim 1, wherein: The third lens, the fifth lens, the eighth lens, and the ninth lens are made of the same low-dispersion optical material, and the optical Abbe number thereof is 95.

1.

6. The optical system of claim 1, wherein: The optical system further comprises a diaphragm arranged between the fourth lens and the fifth lens; the first lens, the second lens, and the third lens before the diaphragm are negative focal powers, the fourth lens is a positive focal power, and the fifth lens, the cemented lens, the eighth lens, and the ninth lens after the diaphragm are all positive focal powers.

7. The optical system of claim 6, wherein: The diaphragm is realized by a spacer ring arranged between the fourth lens and the fifth lens.

8. The optical system of claim 1, wherein: The optical system further comprises a protective window arranged between the ninth lens and an imaging surface.

9. The optical system of claim 1, wherein: The sixth lens and the seventh lens are optically cemented.

10. The optical system of claim 1, wherein: The radii of curvature of the nine optical spherical lenses satisfy the following conditions: The first lens: 15≤R1≤23, 5.0≤R2≤10.0; The second lens: 7≤R1≤16, 3.0≤R2≤8.0; The third lens: -20≤R1≤-13, 3.0≤R2≤7.0; The fourth lens: 7≤R1≤13, -30≤R2≤-23; The fifth lens: -12≤R1≤-5, -8.0≤R2≤-3.5; The sixth lens: 19≤R1≤30, -10.0≤R2≤-2.0; The seventh lens: -10.0≤R1≤-2.0, -21≤R2≤-10; The eighth lens: 15≤R1≤24, -15.0≤R2≤-5.0; The ninth lens: 8≤R1≤15, -60≤R2≤-48; wherein R1 is the curvature of the object side, and R2 is the curvature of the image side.

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