Low-distortion surveying and mapping lens

Abstract

The invention discloses a low-distortion surveying and mapping lens. The low-distortion surveying and mapping lens sequentially comprises a first lens with negative focal power, a second lens with positive focal power, a third lens with positive focal power, a fourth lens with negative focal power, a fifth lens with negative focal power, a sixth lens with negative focal power, a seventh lens with positive focal power, an eighth lens with positive focal power and a ninth lens with negative focal power from an object space to an image space, the fourth lens and the fifth lens form a first cemented lens group, and the sixth lens and the seventh lens form a second cemented lens group. The embodiment of the invention can further reduce optical distortion and can be widely applied to the technical field of optical devices.

Description

Technical Field

[0001] The present invention relates to the technical field of optical devices, and in particular to a low-distortion mapping lens. Background Art

[0002] In surveying and mapping work, lens distortion will affect the accuracy of measurement, especially in applications that require high-precision measurement. Surveying and mapping lenses are very strict about distortion, and the current optical distortion of surveying and mapping lenses cannot meet the application requirements. Summary of the invention

[0003] In view of this, in order to solve one of the above problems, an object of an embodiment of the present invention is to provide a low-distortion mapping lens that can further reduce optical distortion.

[0004] An embodiment of the present invention provides a low-distortion mapping lens, which includes, from the object side to the image side, a first lens with a specific negative optical power, a second lens and a third lens with positive optical power, a fourth lens, a fifth lens and a sixth lens with negative optical power, a seventh lens and an eighth lens with positive optical power, and a ninth lens with negative optical power; the fourth lens and the fifth lens form a first cemented lens group, and the sixth lens and the seventh lens form a second cemented lens group.

[0005] Optionally, the full field angle of the lens satisfies the following relationship:

[0006] 45°<2θ<65°

[0007] Here, 2θ represents the full field of view of the lens.

[0008] Optionally, the total length of the lens and the image plane size of the lens satisfy the following relationship:

[0009] 2 <T / h<3.5

[0010] Among them, T represents the total length of the lens, and h represents the image size of the lens.

[0011] Optionally, the incident angle of the main light of the lens satisfies the following relationship:

[0012] 20 <CRA<26

[0013] Where CRA represents the chief ray incident angle of the lens.

[0014] Optionally, the optical back focal length of the lens and the total length of the lens satisfy the following relationship:

[0015] 0.12 <BFL / T<0.3

[0016] Among them, BFL represents the optical back focal length of the lens, and T represents the total length of the lens.

[0017] Optionally, a material of any one or more of the first lens to the ninth lens includes spherical glass.

[0018] Optionally, the refractive index and Abbe number of the first lens satisfy the following relationship:

[0019] 1.45 <N1<1.6

[0020] 63 <V1<65

[0021] Wherein, N1 represents the refractive index of the first lens, and V1 represents the Abbe number of the first lens.

[0022] Optionally, the refractive index of the third lens satisfies the following relationship:

[0023] 1.8 <N3<2.1

[0024] Wherein, N3 represents the refractive index of the third lens.

[0025] Optionally, the refractive index of the eighth lens satisfies the following relationship:

[0026] 1.85 <N8<2.05

[0027] Here, N8 represents the refractive index of the eighth lens.

[0028] Optionally, the focal length of the lens satisfies the following relationship:

[0029] 35 <f<45

[0030] Where f is the focal length of the lens.

[0031] The implementation of the embodiment of the present invention includes the following beneficial effects: in this embodiment, the low-distortion mapping lens includes nine lenses, including two groups of cemented lens groups. The incident light is shrunk and the chromatic aberration is corrected by the first lens, the third lens controls the aberration, the first cemented lens group and the second cemented lens group further correct the chromatic aberration, and the eighth lens further controls the aberration, thereby further reducing the optical distortion and controlling the optical distortion within 0.2%; in addition, the lens is small and lightweight, which optimizes the quality and size of the lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a structural schematic diagram of a low-distortion mapping lens provided by an embodiment of the present invention;

[0033] Figure 2 is an aberration diagram of a low-distortion mapping lens provided by an embodiment of the present invention;

[0034] Figure 3 is a field curvature diagram of a low-distortion mapping lens provided by an embodiment of the present invention;

[0035] Figure 4 is a peripheral brightness diagram of a low-distortion mapping lens provided by an embodiment of the present invention;

[0036] Figure 5 is a distortion diagram of a low-distortion mapping lens provided by an embodiment of the present invention;

[0037] Figure 6 is an aberration diagram of another low-distortion mapping lens provided by an embodiment of the present invention;

[0038] Figure 7 is a field curvature diagram of another low-distortion mapping lens provided by an embodiment of the present invention;

[0039] Figure 8 This is another peripheral brightness diagram of a low-distortion mapping lens provided by an embodiment of the present invention;

[0040] Fig. 9 This is a distortion diagram of another low-distortion mapping lens provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only provided for the convenience of explanation and description, and the order between the steps is not limited in any way. The execution order of each step in the embodiment can be adaptively adjusted according to the understanding of those skilled in the art.

[0042] like Figure 1 As shown, an embodiment of the present invention provides a low distortion mapping lens, which includes, from the object side to the image side, a first lens L1 with a specific negative optical power, a second lens L2 and a third lens L3 with positive optical power, a fourth lens L4, a fifth lens L5 and a sixth lens L6 with negative optical power, a seventh lens L7 and an eighth lens L8 with positive optical power, and a ninth lens L9 with negative optical power; the fourth lens L4 and the fifth lens L5 form a first cemented lens group, and the sixth lens L6 and the seventh lens L7 form a second cemented lens group.

[0043] Specifically, see Figure 1, the object side S1 of the first lens L1 is convex, and the image side S2 is concave, and the material is glass with low refractive index and high Abbe number, which shrinks the light to correct chromatic aberration; the object side S3 of the second lens L2 is convex, and the image side S4 is concave, and the material is crown glass; the object side S5 of the third lens L3 is convex, and the image side S6 is concave; the object side S7 of the fourth lens L4 is a plane, and the image side S8 is concave; the object side S9 of the fifth lens L5 is convex, and the fourth lens L4 is glued with the fifth lens L5, which is conducive to correcting chromatic aberration; the object side S10 of the sixth lens L6 is concave, and the image side S11 is convex; the object side S12 of the seventh lens L7 is convex, and the sixth lens L6 is glued with the seventh lens L7; the object side S13 of the eighth lens L8 is convex, and the image side S14 is convex; the object side S15 of the ninth lens L9 is concave, and the image side S14 is convex. The first cemented lens group and the second cemented lens group can effectively correct chromatic aberration.

[0044] The glass material used for the lens, the coating requirements, and the design of the black material mechanism inside the lens all effectively control glare suppression.

[0045] Optionally, the full field angle of the lens satisfies the following relationship:

[0046] 45°<2θ<65°

[0047] Here, 2θ represents the full field of view of the lens.

[0048] The full field of view (FOV) is an important concept in optical engineering, which determines the field of view of an optical instrument. The size of the field of view directly affects the performance and application scenarios of optical equipment. The larger the field of view, the wider the field of view, but the optical magnification will decrease accordingly. In layman's terms, when the size of the target object exceeds the field of view, part of the object will not be fully included in the lens.

[0049] Optionally, the total length of the lens and the image plane size of the lens satisfy the following relationship:

[0050] 2 <T / h<3.5

[0051] Among them, T represents the total length of the lens, and h represents the image size of the lens.

[0052] The total length of the lens refers to the distance from the first surface of the lens to the image plane, which reflects the length of the optical components inside the lens.

[0053] Optionally, the incident angle of the main light of the lens satisfies the following relationship:

[0054] 20 <CRA<26

[0055] Where CRA represents the chief ray incident angle of the lens.

[0056] The incident angle of the principal ray refers to the angle between the incident ray and the normal of the lens surface when the ray enters the lens. In optics, the incident angle is the angle between the incident ray and the normal of the incident surface, and the reflection angle is equal to the incident angle. When light enters the lens, it will be reflected and refracted on the lens surface. The smaller the incident angle, the more transmitted light energy and the less reflected light energy. Therefore, the smaller the incident angle of the principal ray of the lens, the higher the clarity of the image. In order to reduce the reflected light energy, a layer of "anti-reflection film" is usually coated on the surface of the lens, which can increase the transmitted light energy and improve the image quality.

[0057] Optionally, the optical back focal length of the lens and the total length of the lens satisfy the following relationship:

[0058] 0.12 <BFL / T<0.3

[0059] Among them, BFL represents the optical back focal length of the lens, and T represents the total length of the lens.

[0060] The optical back focal length (BFL) is defined as the distance from the last side of the lens in the optical system to the image plane. BFL does need to consider multiple factors, including the focal length of the lens, the aperture size, the design of the lens, etc. The reasonable design of BFL can ensure that the light can be correctly focused on the imaging surface, thereby improving the image quality. In addition, the adjustment of BFL can also affect the overall length and weight of the system, which is particularly important for the design of portable devices.

[0061] Optionally, a material of any one or more of the first lens to the ninth lens includes spherical glass.

[0062] Spherical glass can focus more evenly and reduce aberrations, thereby improving imaging quality; compared with flat glass, spherical glass can better correct light refraction, reduce distortion and blur, and make images clearer and more realistic.

[0063] Optionally, the refractive index and Abbe number of the first lens satisfy the following relationship:

[0064] 1.45 <N1<1.6

[0065] 63 <V1<65

[0066] Wherein, N1 represents the refractive index of the first lens, and V1 represents the Abbe number of the first lens.

[0067] The low refractive index and high Abbe number of the first lens can further narrow the light and correct chromatic aberration.

[0068] Optionally, the refractive index of the third lens satisfies the following relationship:

[0069] 1.8 <N3<2.1

[0070] Wherein, N3 represents the refractive index of the third lens.

[0071] The third lens is made of high refractive index material, which can further effectively control aberrations.

[0072] Optionally, the refractive index of the eighth lens satisfies the following relationship:

[0073] 1.85 <N8<2.05

[0074] Here, N8 represents the refractive index of the eighth lens.

[0075] The eighth lens uses a high refractive index material, which can further effectively control aberrations.

[0076] Optionally, the focal length of the lens satisfies the following relationship:

[0077] 35 <f<45

[0078] Where f is the focal length of the lens.

[0079] focal length length Field of view aperture 40mm 65mm 57° F5.6

[0080] The focal length of the lens is determined according to the actual application, and this embodiment does not make any specific restrictions. In a specific embodiment, the focal length of the lens is 40mm, the optical length is 65mm, the field of view angle is 57°, and the aperture is F5.6. The lens has a built-in aperture shutter, and the aperture shutter can be adjusted according to different ambient light to achieve a good imaging effect. In this embodiment, the pixels can reach 60 million.

[0081] The low-distortion mapping lens in this application is described below with two specific embodiments.

[0082] Embodiment 1

[0083] The structural parameters of the low-distortion mapping lens are shown in Table 1, and the focal length and capability values ​​of each lens are shown in Table 2. Among them, OBJ: object plane, STO: aperture, IMA: image plane, R: radius of curvature, D: distance from one surface to the next surface, N: lens refractive index, V: lens Abbe number.

[0084] Table 1

[0085]

[0086]

[0087] Table 2

[0088]

[0089] The aberration, field curvature, peripheral brightness ratio and distortion of the low distortion mapping lens are as follows: Figure 2-Figure 5 Specifically, Figure 2-Figure 5 The wavelength of the middle curve is 435nm-650nm, Figure 2 The medium aberration is controlled in the range of (-2μm-4μm). Figure 3 The mid-meridian field curvature and sagittal field curvature are controlled within the range of (-0.2mm-0.2mm); because the surveying and mapping has strict requirements on distortion, the lens distortion is controlled within 0.2%. Figure 4 The peripheral light ratio of the lens is not less than 40% at an image height of 21.5mm; Figure 5 The Airy disk in the center field of the midpoint diagram is controlled within 1.5μm. Figure 2-Figure 5 The results show that the lens can restore the true proportions in surveying and mapping shooting, with small distortion and good chromatic aberration correction.

[0090] Embodiment 2

[0091] The structural parameters of the low-distortion mapping lens are shown in Table 3, and the focal length and capability values ​​of each lens are shown in Table 4. Among them, OBJ: object plane, STO: aperture, IMA: image plane, R: radius of curvature, D: distance from one surface to the next surface, N: lens refractive index, V: lens Abbe number.

[0092] Table 3

[0093]

[0094]

[0095] Table 4

[0096]

[0097]

[0098] The aberration, field curvature, peripheral brightness ratio and distortion of the low distortion mapping lens are as follows: Figure 6-Figure 9 Specifically, Figure 6-Figure 9 The wavelength of the middle curve is 435nm-650nm; Figure 6 The medium aberration is controlled in the range of (-2μm-4μm); Figure 7 The mid-meridian field curvature and sagittal field curvature are controlled within the range of (-0.2mm-0.2mm); because the surveying and mapping has strict requirements on distortion, the lens distortion is controlled within 0.2%; Figure 8 The peripheral light ratio of the lens is not less than 40% at an image height of 21.5mm; Fig. 9 The Airy disk in the center field of the midpoint diagram is controlled within 1.5μm. Figure 6-Figure 9 The results show that the lens can restore the true proportions in surveying and mapping shooting, with small distortion and good chromatic aberration correction.

[0099] The implementation of the embodiment of the present invention includes the following beneficial effects: in this embodiment, the low-distortion mapping lens includes nine lenses, including two groups of cemented lens groups. The incident light is shrunk and the chromatic aberration is corrected by the first lens, the third lens controls the aberration, the first cemented lens group and the second cemented lens group further correct the chromatic aberration, and the eighth lens further controls the aberration, thereby further reducing the optical distortion and controlling the optical distortion within 0.2%; in addition, the lens is small and lightweight, which optimizes the quality and size of the lens.

[0100] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A low distortion mapping lens, characterized in that: The invention comprises, from the object side to the image side, a first lens with specific negative optical power, a second lens and a third lens with positive optical power, a fourth lens, a fifth lens and a sixth lens with negative optical power, a seventh lens and an eighth lens with positive optical power, and a ninth lens with negative optical power; the fourth lens and the fifth lens form a first cemented lens group, and the sixth lens and the seventh lens form a second cemented lens group.

2. The low distortion mapping lens according to claim 1, characterized in that: The full field of view of the lens satisfies the following relationship: 45°<2θ<65° Here, 2θ represents the full field of view of the lens.

3. The low distortion mapping lens according to claim 1, characterized in that: The total length of the lens and the image plane size of the lens satisfy the following relationship: 2 <T / h<3.5 Among them, T represents the total length of the lens, and h represents the image size of the lens.

4. The low distortion mapping lens according to claim 1, characterized in that: The incident angle of the principal ray of the lens satisfies the following relationship: 20 <CRA<26 Where CRA represents the chief ray incident angle of the lens.

5. The low distortion mapping lens according to claim 1, characterized in that: The optical back focal length of the lens and the total length of the lens satisfy the following relationship: 0.12 <BFL / T<0.3 Among them, BFL represents the optical back focal length of the lens, and T represents the total length of the lens.

6. The low distortion mapping lens according to claim 1, characterized in that: A material of any one or more of the first to ninth lenses includes spherical glass.

7. The low distortion mapping lens according to claim 1, characterized in that: The refractive index and Abbe number of the first lens satisfy the following relationship: 1.45<N1<1.6 63<V1<65 Wherein, N1 represents the refractive index of the first lens, and V1 represents the Abbe number of the first lens.

8. The low distortion mapping lens according to claim 1, characterized in that: The refractive index of the third lens satisfies the following relationship: 1.8<N3<2.1 Wherein, N3 represents the refractive index of the third lens.

9. The low distortion mapping lens according to claim 1, characterized in that: The refractive index of the eighth lens satisfies the following relationship: 1.85<N8<2.05 Here, N8 represents the refractive index of the eighth lens.

10. The low distortion mapping lens according to claim 1, characterized in that: The focal length of the lens satisfies the following relationship: 35<f<45 Where f is the focal length of the lens.

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