Ultra-wide-angle near-infrared imaging system

Abstract

The utility model discloses an ultra-wide-angle near-infrared imaging system. A first lens (G1), a second lens (L2), a third lens (G3), a diaphragm (STO), a fourth lens (L4), a fifth lens (L5), a sixth lens (L6) and an optical filter (IR) are sequentially arranged from an object plane to an image plane; the effective surface calibers of the first lens and the second lens are large, so that the field angle is large, and the F number is small; the lens type adopts a spherical surface and an aspheric surface, and the negative lens and the positive lens are combined with each other, so that aberration reduction and f theta distortion control are facilitated, the imaging effect is good, and the MTF at the cut-off frequency is high; the second, fourth, fifth and sixth lenses are made of plastic materials, so that the cost is controlled.

Description

[Technical Field]

[0001] This invention relates to optical lens imaging systems, specifically an ultra-wide-angle near-infrared imaging system. [Background Technology]

[0002] As virtual reality technology matures, more and more AR products are becoming known and used. For user experience, the field of view and image quality of AR products greatly influence the user experience. Many AR products fail to achieve a wide field of view, resulting in a small image area; conversely, a wide field of view can lead to significant distortion, poor image quality, and other problems. This invention addresses this issue by designing an ultra-wide-angle near-infrared imaging system. [Summary of the Invention]

[0003] In response to the needs of the existing market and based on research into areas for improvement, this invention provides an ultra-wide-angle near-infrared imaging system. Its purpose is to solve the technical problem that current ultra-wide-angle near-infrared imaging systems cannot simultaneously guarantee a large field of view, low distortion, and high imaging quality.

[0004] To achieve the above objectives, the present invention provides an ultra-wide-angle near-infrared imaging system, comprising a first lens (G1), a second lens (L2), a third lens (G3), an aperture stop (STO), a fourth lens (L4), a fifth lens (L5), a sixth lens (L6), and an IR filter arranged sequentially from the object plane to the image plane.

[0005] The first lens (G1) is a negative lens made of glass, with a focal length satisfying -6.0 < f1 / f < -5.0; the object side is convex and spherical, and the image side is concave and spherical.

[0006] The second lens (L2) is a negative lens made of plastic, with a focal length satisfying -2.0 < f2 / f < -1.0; the object side is convex and aspherical, and the image side is concave and aspherical.

[0007] The third lens (G3) is a positive lens made of glass, with a focal length satisfying 1.5 < f3 / f < 2.0; the object-side surface is convex and spherical, and the image-side surface is also convex and spherical.

[0008] The fourth lens (L4) is a negative lens made of plastic, with a focal length satisfying -10.0 < f4 / f < -9.0; the object side is convex and aspherical, and the image side is concave and aspherical.

[0009] The fifth lens (L5) is a positive lens made of plastic, with a focal length satisfying 5.0 < f5 / f < 6.0; the object side is concave and aspherical, and the image side is convex and aspherical.

[0010] The sixth lens (L6) is a positive lens made of plastic, with a focal length satisfying 2.0 < f6 / f < 3.0; the object side is convex and aspherical, and the image side is concave and aspherical.

[0011] This ultra-wide-angle near-infrared imaging system satisfies the following relationship:

[0012] 18.0 < TTL / f < 20.0;

[0013] TTL < 11mm;

[0014] 4.0 < F / f < 4.5;

[0015] Where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, TTL is the on-axis distance from the object side of the first lens to the imaging plane; f is the effective focal length of the ultra-wide-angle near-infrared imaging system, and F is the F-number of the ultra-wide-angle near-infrared imaging system.

[0016] Preferably, the ultra-wide-angle near-infrared imaging system satisfies the following relationship:

[0017] 23 < Y1 / f < 25;

[0018] 8 < Y² / f < 10;

[0019] 230° < FOV < 235°;

[0020] Where Y1 is the effective aperture of the object side (S1) of the first lens (G1), Y2 is the effective aperture of the object side (S3) of the second lens (L2), f is the effective focal length of the ultra-wide-angle near-infrared imaging system, and FOV is the maximum field of view of this ultra-wide-angle near-infrared imaging system.

[0021] Preferably, the ultra-wide-angle near-infrared imaging system satisfies the following relationship:

[0022] 3.0 < T12 / f < 3.5;

[0023] 3.5 < T23 / f < 4.0;

[0024] 1.5 < T34 / f < 2.0;

[0025] 0.08 < T45 / f < 0.1;

[0026] 0.01 < T56 / f < 0.02;

[0027] 0.30 < T1 / ∑T < 0.35;

[0028] 0.10 < T² / ∑T < 0.15;

[0029] 0.25 < T3 / ∑T < 0.30;

[0030] 0.05 < T₄ / ∑T < 0.10;

[0031] 0.10 < T5 / ∑T < 0.15;

[0032] 0.10 < T6 / ∑T < 0.15;

[0033] Where T12 is the air gap between the first and second lenses on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, T34 is the air gap between the third and fourth lenses on the optical axis, T45 is the air gap between the fourth and fifth lenses on the optical axis, T56 is the air gap between the fifth and sixth lenses on the optical axis, and f is the effective focal length of the ultra-wide-angle near-infrared imaging system. ∑T is the sum of the lens thicknesses of the first, second, third, fourth, fifth, and sixth lenses on the optical axis, and T1, T2, T3, T4, T5, and T6 are the lens thicknesses of the first, second, third, fourth, fifth, and sixth lenses on the optical axis, respectively.

[0034] In summary, compared with the prior art, the above-described technical solutions conceived by this invention can achieve the following beneficial effects:

[0035] 1. In the ultra-wide-angle near-infrared imaging system described above, the effective surface diameters of the first lens (G1) and the second lens (L2) are both large, which is beneficial to increasing the field of view; the effective focal length of the fourth lens is large, which is beneficial to reducing aberrations; while the F-number is small, the air gap between the fourth lens, the fifth lens and the sixth lens is small, resulting in good depth of field.

[0036] 2. In the ultra-wide-angle near-infrared imaging system, the aperture stop is located between the image side of the third lens and the object side of the fourth lens. The second and third lenses, the fourth and fifth lenses are a combination of negative and positive lenses. Furthermore, the second, fourth, fifth and sixth lenses are aspherical lenses, which helps to control distortion and improve imaging quality. At the limiting frequency, the MTF is greater than 45%. [Attached Image Description]

[0037] Figure 1 This is a schematic diagram of the structure of the ultra-wide-angle near-infrared imaging system.

[0038] Figure 2 This is the MTF diagram of the ultra-wide-angle near-infrared imaging system.

Detailed Implementation Methods

[0039] To explain the purpose and technical solutions of this invention in detail, embodiments will be described in conjunction with them, and the accompanying drawings are all data from this embodiment. It can be said that the data of the embodiments disclosed in this invention are complete, but not limited to this embodiment. The technical features involved can be explained and described in this embodiment.

[0040] The ultra-wide-angle near-infrared imaging system proposed in this invention includes a first lens (G1), a second lens (L2), a third lens (G3), an aperture stop (STO), a fourth lens (L4), a fifth lens (L5), a sixth lens (L6), and an IR filter arranged sequentially from the object plane to the image plane.

[0041] The first lens (G1) is a negative lens made of glass, with a focal length satisfying -6.0 < f1 / f < -5.0; the object side is convex and spherical, and the image side is concave and spherical.

[0042] The second lens (L2) is a negative lens made of plastic, with a focal length satisfying -2.0 < f2 / f < -1.0; the object side is convex and aspherical, and the image side is concave and aspherical.

[0043] The third lens (G3) is a positive lens made of glass, with a focal length satisfying 1.5 < f3 / f < 2.0; the object-side surface is convex and spherical, and the image-side surface is also convex and spherical.

[0044] The fourth lens (L4) is a negative lens made of plastic, with a focal length satisfying -10.0 < f4 / f < -9.0; the object side is convex and aspherical, and the image side is concave and aspherical.

[0045] The fifth lens (L5) is a positive lens made of plastic, with a focal length satisfying 5.0 < f5 / f < 6.0; the object side is concave and aspherical, and the image side is convex and aspherical.

[0046] The sixth lens (L6) is a positive lens made of plastic, with a focal length satisfying 2.0 < f6 / f < 3.0; the object side is convex and aspherical, and the image side is concave and aspherical.

[0047] This ultra-wide-angle near-infrared imaging system satisfies the following relationship:

[0048] 18.0 < TTL / f < 20.0;

[0049] TTL < 11mm;

[0050] 4.0 < F / f < 4.5;

[0051] Where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, TTL is the on-axis distance from the object side of the first lens to the imaging plane; f is the effective focal length of the ultra-wide-angle near-infrared imaging system, and F is the F-number of the ultra-wide-angle near-infrared imaging system. In this optical system, the second and third lenses, and the fourth and fifth lenses, combine negative and positive lenses. Furthermore, the second, fourth, fifth, and sixth lenses are aspherical lenses. The fourth lens has a large focal length, which is beneficial for controlling aberrations, while the other lenses have small focal lengths, which is beneficial for controlling fθ distortion. Wide-angle lenses inevitably produce distortion. When the angle exceeds a certain degree, fθ distortion is used for evaluation, which is essentially the relationship between the actual image height and the ideal image height. In this invention, the fθ distortion is less than 5%, which helps improve image quality. Moreover, the total length TTL is less than 11 mm, which helps reduce the size of the optical system. The IR filter used allows near-infrared light to pass through while filtering out other wavelengths. A smaller F-number in the optical system results in a larger aperture; this optical system has an F / f of no more than 4.5, and satisfies the requirement of being greater than 4, providing a suitable depth of field to meet imaging needs. Four of the lens elements are made of plastic, saving costs and making them easy to manufacture.

[0052] Preferably, the ultra-wide-angle near-infrared imaging system is characterized by satisfying the following relationship:

[0053] 23 < Y1 / f < 25;

[0054] 8 < Y² / f < 10;

[0055] 230° < FOV < 235°;

[0056] Where Y1 is the effective aperture of the object-side surface (S1) of the first lens (G1), Y2 is the effective aperture of the object-side surface (S3) of the second lens (L2), f is the effective focal length of the ultra-wide-angle near-infrared imaging system, and FOV is the maximum field of view of this ultra-wide-angle near-infrared imaging system. The effective apertures of both the first lens (G1) and the second lens (L2) are relatively large, and their ratios to the effective focal length of the system are both greater than 8. The large aperture and symmetrical design are conducive to achieving a large field of view.

[0057] Preferably, the ultra-wide-angle near-infrared imaging system is characterized by satisfying the following relationship:

[0058] 3.0 < T12 / f < 3.5;

[0059] 3.5 < T23 / f < 4.0;

[0060] 1.5 < T34 / f < 2.0;

[0061] 0.08 < T45 / f < 0.1;

[0062] 0.01 < T56 / f < 0.02;

[0063] 0.30 < T1 / ∑T < 0.35;

[0064] 0.10 < T² / ∑T < 0.15;

[0065] 0.25 < T3 / ∑T < 0.30;

[0066] 0.05 < T₄ / ∑T < 0.10;

[0067] 0.10 < T5 / ∑T < 0.15;

[0068] 0.10 < T6 / ∑T < 0.15;

[0069] Where T12 is the air gap between the first and second lenses on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, T34 is the air gap between the third and fourth lenses on the optical axis, T45 is the air gap between the fourth and fifth lenses on the optical axis, T56 is the air gap between the fifth and sixth lenses on the optical axis, and f is the effective focal length of the ultra-wide-angle near-infrared imaging system. ∑T is the sum of the lens thicknesses of the first, second, third, fourth, fifth, and sixth lenses on the optical axis, respectively. T1, T2, T3, T4, T5, and T6 are the lens thicknesses of the first, second, third, fourth, fifth, and sixth lenses on the optical axis, respectively. The small air gaps and thin lenses between the fourth, fifth, and sixth lenses result in a small optical system size, contributing to miniaturization. The maximum thickness ratio of each lens is also less than 0.35, which helps reduce aberrations, meet depth-of-field requirements, and improve image clarity. The MTF of this imaging system is greater than 45% at the cutoff frequency.

[0070] The following table is a lens data sheet for an embodiment.

[0071] Table 1 Lens data for the ultra-wide-angle near-infrared imaging system

[0072] Surface number Surface type Radius of curvature (mm) Thickness (mm) Material (Refractive Index: Abbe Number) surface spherical unlimited 317.2275 S1 spherical 10.2997 1.4185 1.73：44.9 S2 spherical 2.8585 1.8286 S3 aspherical 5.1332 0.5401 1.52：55.7 S4 aspherical 0.7151 1.8901 S5 spherical 2.7071 1.3226 1.73：27.5 S6 spherical -2.5150 0.2980 aperture spherical unlimited 0.3662 S8 aspherical 2.6859 0.2501 1.62：22.4 S9 aspherical 1.8062 0.1911 S10 aspherical -5.1121 0.3738 1.57：29.9 S11 aspherical -1.9777 0.0100 S12 aspherical 1.6540 0.6701 1.52：55.7 S13 aspherical -7.5220 0.1100 S14 spherical unlimited 0.6100 1.52：64.2 S15 spherical unlimited 0.3300 Image spherical unlimited -0.0003

[0073] Table 2 Surface coefficients of aspherical lenses in ultra-wide-angle near-infrared imaging systems

[0074]

[0075] The methods described in this specification are merely preferred embodiments and are not intended to limit the inventive concept and design techniques. Anything that does not depart from the inventive concept and design techniques should fall within the protection scope of this invention.

Claims

1. An ultra-wide-angle near-infrared imaging system, characterized in that: The first lens (G1), second lens (L2), third lens (G3), aperture stop (STO), fourth lens (L4), fifth lens (L5), sixth lens (L6), and filter (IR) are arranged sequentially from the object plane to the image plane. The first lens (G1) is a negative lens made of glass, with a focal length satisfying -6.0 < f1 / f < -5.0; the object side is convex and spherical, and the image side is concave and spherical. The second lens (L2) is a negative lens made of plastic, with a focal length satisfying -2.0 < f2 / f < -1.0; the object side is convex and aspherical, and the image side is concave and aspherical. The third lens (G3) is a positive lens made of glass, with a focal length satisfying 1.5 < f3 / f < 2.0; the object-side surface is convex and spherical, and the image-side surface is also convex and spherical. The fourth lens (L4) is a negative lens made of plastic, with a focal length satisfying -10.0 < f4 / f < -9.0; the object side is convex and aspherical, and the image side is concave and aspherical. The fifth lens (L5) is a positive lens made of plastic, with a focal length satisfying 5.0 < f5 / f < 6.0; the object side is concave and aspherical, and the image side is convex and aspherical. The sixth lens (L6) is a positive lens made of plastic, with a focal length satisfying 2.0 < f6 / f < 3.0; the object side is convex and aspherical, and the image side is concave and aspherical. This ultra-wide-angle near-infrared imaging system satisfies the following relationship: 18.0 < TTL / f < 20.0; TTL < 11mm; 4.0 < F / f < 4.5; Where f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, TTL is the on-axis distance from the object side of the first lens to the imaging plane; f is the effective focal length of the ultra-wide-angle near-infrared imaging system, and F is the F-number of the ultra-wide-angle near-infrared imaging system.

2. The ultra-wide-angle near-infrared imaging system as described in claim 1, characterized in that... The following relationship must be satisfied: 23 < Y1 / f < 25; 8 < Y² / f < 10; 230° < FOV < 235°; Where Y1 is the effective aperture of the object side (S1) of the first lens (G1), Y2 is the effective aperture of the object side (S3) of the second lens (L2), f is the effective focal length of the ultra-wide-angle near-infrared imaging system, and FOV is the maximum field of view of this ultra-wide-angle near-infrared imaging system.

3. The ultra-wide-angle near-infrared imaging system as described in claim 1, characterized in that... The following relationship must be satisfied: 3.0 < T12 / f < 3.5; 3.5 < T23 / f < 4.0; 1.5 < T34 / f < 2.0; 0.08 < T45 / f < 0.1; 0.01 < T56 / f < 0.02; 0.30 < T1 / ∑T < 0.35; 0.10 < T² / ∑T < 0.15; 0.25 < T3 / ∑T < 0.30; 0.05 < T₄ / ∑T < 0.10; 0.10 < T5 / ∑T < 0.15; 0.10 < T6 / ∑T < 0.15; Wherein, T12 is the air gap between the first and second lenses on the optical axis, T23 is the air gap between the second and third lenses on the optical axis, T34 is the air gap between the third and fourth lenses on the optical axis, T45 is the air gap between the fourth and fifth lenses on the optical axis, T56 is the air gap between the fifth and sixth lenses on the optical axis, f is the effective focal length of the ultra-wide-angle near-infrared imaging system, ∑T is the sum of the lens thicknesses of the first, second, third, fourth, fifth, and sixth lenses on the optical axis, and T1, T2, T3, T4, T5, and T6 are the lens thicknesses of the first, second, third, fourth, fifth, and sixth lenses on the optical axis, respectively.

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