Infrared confocal lens

Abstract

The utility model discloses an infrared confocal lens, which relates to the technical field of optics, is provided with an object side and an image side which are correspondingly arranged along the direction of an optical axis, and comprises 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 an image surface which are sequentially arranged from the object side to the image side, the total optical length of the infrared confocal lens is controlled within 22.5 mm, the field angle can reach 157 degrees, and the infrared confocal lens meets the following conditions:-0.67 < = phi 1 / phi < =-0.25; 0.60 < = phi 2 / phi < = 0.4; 0.35 < = phi 3 / phi < = 0.3; 0.3 < = phi 4 / phi < = 0.6; -0.55 < = phi 5 / phi < = 0.45; 0.4 < = phi 6 / phi < = 0.6; -0.8 < = phi 7 / phi < =-0.2; 0.3 < = phi 8 / phi < = 0.7; the first lens is a glass spherical lens or a plastic aspheric lens, the second lens, the third lens, the seventh lens and the eighth lens are plastic aspheric lenses, and the fourth lens, the fifth lens and the sixth lens are glass spherical lenses. The infrared confocal lens has a large field angle and a wide visual field range, can adapt to high and low temperature environments, and is clear in imaging at the temperature ranging from-40 DEG C to 80 DEG C.

Description

Technical Field

[0001] The utility model relates to the technical field of optics, in particular to an infrared confocal lens. Background Art

[0002] Since security monitoring needs to be carried out uninterruptedly around the clock, clear imaging in low light and at night is crucial. At present, some starlight-level cameras have appeared on the market, but there are still some performance defects that limit their use scenarios, and they cannot achieve infrared confocal function while meeting the requirements of small size. Utility Model Content

[0003] The main purpose of the utility model is to provide an infrared confocal lens, aiming to achieve the infrared confocal function under the premise of meeting the requirements of small volume.

[0004] To achieve the above-mentioned purpose, the utility model proposes an infrared confocal lens, the infrared confocal lens has an object side and an image side correspondingly arranged along the optical axis direction, the infrared confocal lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens and an image plane arranged in sequence from the object side to the image side, so that the total optical length of the infrared confocal lens is controlled within 22.5 mm, and the field of view angle can reach 157°, the optical focal power of the infrared confocal lens is φ, the optical focal power of the first lens is φ1, the optical focal power of the second lens is φ2, the optical focal power of the third lens is φ3, the optical focal power of the fourth lens is φ4, the optical focal power of the fifth lens is φ5, the optical focal power of the sixth lens is φ6, the optical focal power of the seventh lens is φ7, and the optical focal power of the eighth lens is φ8, and the infrared confocal lens meets the following conditions:

[0005] -0.67≤φ1 / φ≤-0.25; -0.60≤φ2 / φ≤0.4; -0.35≤φ3 / φ≤0.3; 0.3≤φ4 / φ≤0.6; -0.55≤φ5 / φ≤0.45; -0.4≤φ6 / φ≤0.6; -0.8≤φ7 / φ≤-0.2; 0.3≤φ8 / φ≤0.7;

[0006] Among them, the first lens is a glass spherical lens or a plastic aspherical lens, the second lens, the third lens, the seventh lens and the eighth lens are plastic aspherical lenses, and the fourth lens, the fifth lens and the sixth lens are glass spherical lenses.

[0007] In one embodiment, the refractive index of the first lens is n1, 1.50≤n1≤1.60;

[0008] The refractive index of the second lens is n2, 1.50≤n2≤1.75;

[0009] The refractive index of the third lens is n3, 1.50≤n3≤1.70;

[0010] The refractive index of the fourth lens is n4, 1.41≤n4≤1.70;

[0011] The refractive index of the fifth lens is n5, 1.70≤n5≤1.90;

[0012] The refractive index of the sixth lens is n6, 1.41≤n6≤1.70;

[0013] The refractive index of the seventh lens is n7, 1.60≤n7≤1.75;

[0014] The refractive index of the eighth lens is n8, 1.50≤n8≤1.60.

[0015] In one embodiment, the dispersion coefficient of the first lens is v1, 50.0≤v1≤65.0;

[0016] The dispersion coefficient of the second lens is v2, 20.0≤v2≤65.0;

[0017] The dispersion coefficient of the third lens is v3, 18.0≤v3≤25.0;

[0018] The dispersion coefficient of the fourth lens is v4, 60.0≤v4≤95.0;

[0019] The dispersion coefficient of the fifth lens is v5, 18.0≤v5≤30.0;

[0020] The dispersion coefficient of the sixth lens is v6, 60.0≤v6≤95.0;

[0021] The dispersion coefficient of the seventh lens is v7, 15.0≤v7≤25.0;

[0022] The dispersion coefficient of the eighth lens is v8, 50.0≤v8≤60.0.

[0023] In one implementation, the aperture value of the infrared confocal lens is F, 0.8≤F≤1.1.

[0024] In one implementation, the focal length of the infrared confocal lens is f, the entrance pupil diameter of the infrared confocal lens is d, and 0.8≤f / d≤1.1.

[0025] In one implementation, the back focus of the infrared confocal lens is BFL, the total length of the lens is TTL, and BFL / TTL≥0.1.

[0026] In one implementation, the fifth lens and the sixth lens are cemented together.

[0027] In one embodiment, the infrared confocal lens further includes an aperture stop, and the aperture stop is disposed between the second lens and the third lens.

[0028] In one embodiment, the infrared confocal lens further includes a photosensitive chip, and the photosensitive chip is disposed on a side of the eighth lens close to the image side.

[0029] In one embodiment, the infrared confocal lens further includes a protective glass, and the protective glass is disposed between the eighth lens and the photosensitive chip.

[0030] The technical solution of the utility model adopts eight lenses to form an optical system, wherein the first lens is a glass spherical lens or a plastic aspherical lens, the second lens, the third lens, the seventh lens and the eighth lens are plastic aspherical lenses, the aspherical lens has a better curvature radius characteristic, has the advantages of improving distortion aberration and improving astigmatism aberration, and after adopting the aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality of the lens, and at the same time, the use of the plastic aspherical lens can also reduce the manufacturing cost of the projection optical system, the fourth lens, the fifth lens and the sixth lens are glass spherical lenses, the glass lens can well resist the problem of lens deformation due to heat, reduce the influence of temperature on the optical performance of the lens, and maintain the high precision of the lens for a long time, the total optical length of the infrared confocal lens is controlled within 22.5mm, and the field of view angle can reach 157°, so that the infrared confocal lens has a large field of view angle, has a wider field of view range, and can adapt to high and low temperature environments, and can image clearly within the temperature range of -40℃ to +80℃. To provide a small, lightweight lens with infrared confocal function. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0032] Figure 1 A schematic structural diagram of an embodiment of an infrared confocal lens provided by the utility model;

[0033] Figure 2 for Figure 1 RAY FAN curve of the mid-infrared confocal lens in the visible light band;

[0034] Figure 3 for Figure 1RAY FAN curve of the infrared band of the mid-infrared confocal lens;

[0035] Figure 4 for Figure 1 Field curvature distortion diagram of a mid-infrared confocal lens.

[0036] Description of Figure Numbers:

[0037] 100. Infrared confocal lens; 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Aperture; 10. Protective glass; 11. Photosensitive chip.

[0038] The realization of the purpose, functional features and advantages of the utility model will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0040] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0041] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the utility model, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of the features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the utility model.

[0042] The utility model provides an infrared confocal lens, which aims to realize the infrared confocal function under the premise of meeting the requirement of small volume.

[0043] See also Figure 1 In one embodiment of the utility model, the infrared confocal lens 100 has an object side and an image side correspondingly arranged along the optical axis direction. The infrared confocal lens 100 includes 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 and an eighth lens 8 and an image plane arranged in sequence from the object side to the image side, so that the total optical length of the infrared confocal lens 100 is controlled within 22.5 mm, and the field of view angle can reach 157°. The optical focal power of the infrared confocal lens 100 is φ, the optical focal power of the first lens 1 is φ1, the optical focal power of the second lens 2 is φ2, the optical focal power of the third lens 3 is φ3, the optical focal power of the fourth lens 4 is φ4, the optical focal power of the fifth lens 5 is φ5, and the optical focal power of the sixth lens 6 is φ 6, the focal power of the seventh lens 7 is φ7, the focal power of the eighth lens 8 is φ8, and the infrared confocal lens 100 satisfies the following conditions: -0.67≤φ1 / φ≤-0.25; -0.60≤φ2 / φ≤0.4; -0.35≤φ3 / φ≤0.3; 0.3≤φ4 / φ≤0.6; -0.55≤φ5 / φ≤0.45; -0.4≤φ6 / φ≤0.6; -0.8≤φ7 / φ≤-0.2; 0.3≤φ8 / φ≤0.7; the first lens 1 is a glass spherical lens or a plastic aspherical lens, the second lens 2, the third lens 3, the seventh lens 7 and the eighth lens 8 are plastic aspherical lenses, and the fourth lens 4, the fifth lens 5 and the sixth lens 6 are glass spherical lenses.

[0044] The technical solution of the utility model adopts eight lenses to form an optical system, wherein the first lens 1 is a glass spherical lens or a plastic aspherical lens, the second lens 2, the third lens 3, the seventh lens 7 and the eighth lens 8 are plastic aspherical lenses, and the aspherical lens has a better curvature radius characteristic, and has the advantages of improving distortion aberration and improving astigmatism aberration. After adopting the aspherical lens, the aberration occurring during imaging can be eliminated as much as possible, thereby improving the imaging quality of the lens. At the same time, the use of the plastic aspherical lens can also reduce the manufacturing cost of the projection optical system, the fourth lens 4, the fifth lens 5 and the sixth lens 6 are glass spherical lenses, and the glass lens can well resist the problem of lens deformation due to heat, reduce the influence of temperature on the optical performance of the lens, and maintain the high precision of the lens for a long time, the total optical length of the infrared confocal lens 100 is controlled within 22.5mm, and the field of view angle can reach 157°, so that the infrared confocal lens 100 has a large field of view angle, a wide field of view range, and can adapt to high and low temperature environments, and can image clearly within the temperature range of -40℃ to +80℃. To provide a small, lightweight lens with infrared confocal function.

[0045] It can be understood that in the embodiment of the present invention, multiple lenses adopt a glass-plastic hybrid structure, fully utilizing aspheric surfaces to reduce the volume of the optical system, while greatly reducing the cost of the infrared confocal lens 100.

[0046] It should be noted that the present invention does not limit the specific type of the first lens 1. For example, in one embodiment of the present invention, the first lens 1 is configured as a glass spherical lens. Such a configuration enables the first lens 1 to better correct aberrations at large apertures.

[0047] In another embodiment of the present invention, the first lens 1 is configured as a plastic aspheric lens. Such a configuration can facilitate the collection of light in the optical system, effectively increase the field of view, correct distortion and reduce the volume.

[0048] In an embodiment of the present invention, the fifth lens 5 and the sixth lens 6 are fully bonded and connected, so that the chromatic aberration of the infrared confocal lens 100 can be better corrected.

[0049] It should be noted that, in the embodiments of the present invention, the optical focal power φ1 of the first lens 1, the optical focal power φ2 of the second lens 2, the optical focal power φ3 of the third lens 3, the optical focal power φ4 of the fourth lens 4, the optical focal power φ5 of the fifth lens 5, the optical focal power φ6 of the sixth lens 6, the optical focal power φ7 of the seventh lens 7 and the optical focal power φ8 of the eighth lens 8 can also be set to any value within a range, and the present invention does not impose any restriction on this.

[0050] Further, the refractive index of the first lens 1 is n1, 1.50≤n1≤1.60; the refractive index of the second lens 2 is n2, 1.50≤n2≤1.75; the refractive index of the third lens 3 is n3, 1.50≤n3≤1.70; the refractive index of the fourth lens 4 is n4, 1.41≤n4≤1.70; the refractive index of the fifth lens 5 is n5, 1.70≤n5≤1.90; the refractive index of the sixth lens 6 is n6, 1.41≤n6≤1.70; the refractive index of the seventh lens 7 is n7, 1.60≤n7≤1.75; the refractive index of the eighth lens 8 is n8, 1.50≤n8≤1.60.

[0051] Similarly, the present invention does not limit the refractive index of the first lens 1, the refractive index of the second lens 2, the refractive index of the third lens 3, the refractive index of the fourth lens 4, the refractive index of the fifth lens 5, the refractive index of the sixth lens 6, the refractive index of the seventh lens 7 and the refractive index of the eighth lens 8.

[0052] It should be noted that, in the embodiments of the present invention, the refractive index n1 of the first lens 1, the refractive index n2 of the second lens 2, the refractive index n3 of the third lens 3, the refractive index n4 of the fourth lens 4, the refractive index n5 of the fifth lens 5, the refractive index n6 of the sixth lens 6, the refractive index n7 of the seventh lens 7, and the refractive index n8 of the eighth lens 8 can also be set to any value within a range, and the present invention does not impose any limitation on this.

[0053] In addition, in the utility model, the dispersion coefficient of the first lens 1 is v1, 50.0≤v1≤65.0; the dispersion coefficient of the second lens 2 is v2, 20.0≤v2≤65.0; the dispersion coefficient of the third lens 3 is v3, 18.0≤v3≤25.0; the dispersion coefficient of the fourth lens 4 is v4, 60.0≤v4≤95.0; the dispersion coefficient of the fifth lens 5 is v5, 18.0≤v5≤30.0; the dispersion coefficient of the sixth lens 6 is v6, 60.0≤v6≤95.0; the dispersion coefficient of the seventh lens 7 is v7, 15.0≤v7≤25.0; the dispersion coefficient of the eighth lens 8 is v8, 50.0≤v8≤60.0.

[0054] The present utility model also does not limit the dispersion coefficient v1 of the first lens 1, the dispersion coefficient v2 of the second lens 2, the dispersion coefficient v3 of the third lens 3, the dispersion coefficient v4 of the fourth lens 4, the dispersion coefficient v5 of the fifth lens 5, the dispersion coefficient v6 of the sixth lens 6, the dispersion coefficient v7 of the seventh lens 7, and the dispersion coefficient v8 of the eighth lens 8.

[0055] Similarly, in the embodiments of the present invention, the dispersion coefficient v1 of the first lens 1, the dispersion coefficient v2 of the second lens 2, the dispersion coefficient v3 of the third lens 3, the dispersion coefficient v4 of the fourth lens 4, the dispersion coefficient v5 of the fifth lens 5, the dispersion coefficient v6 of the sixth lens 6, the dispersion coefficient v7 of the seventh lens 7, and the dispersion coefficient v8 of the eighth lens 8 can also be set to any value within a range, and the present invention does not impose any limitation on this.

[0056] Furthermore, since the aperture of the existing monitoring lens is small and cannot meet the monitoring requirements of low-light environments, in order to solve the above problem, the aperture value of the infrared confocal lens 100 is F, 0.8≤F≤1.1. Such a setting can enable the infrared confocal lens 100 to support a 1 / 2.5-inch image plane and enable the infrared confocal lens 100 to have a large light flux and high image brightness.

[0057] Specifically, the focal length of the infrared confocal lens 100 is f, the entrance pupil diameter of the infrared confocal lens 100 is d, and 0.8≤f / d≤1.1. It can be understood that when the focal length f of the infrared confocal lens 100 and the entrance pupil diameter d of the infrared confocal lens 100 satisfy the above relationship, the fixed-focus lens has the characteristics of a super-large aperture, and can still have excellent imaging effects in low-illuminance environments, and can meet the imaging requirements of bright and dark environments.

[0058] Furthermore, the back focus of the infrared confocal lens 100 is BFL, the total length of the lens is TTL, and BFL / TTL≥0.1.

[0059] In addition, it should be noted that the infrared confocal lens 100 further includes an aperture 9, and the aperture 9 is disposed between the second lens 2 and the third lens 3. The aperture 9 is used to adjust the light flux according to actual conditions to improve the imaging quality.

[0060] Furthermore, the infrared confocal lens 100 further includes a protective glass 10 and a photosensitive chip 11 arranged in sequence from the object side to the image side, and the protective glass 10 and the photosensitive chip 11 are arranged on the side of the eighth lens 8 close to the image side. The protective glass 10 can provide effective protection for the photosensitive chip 11, and the protective glass 10 can be set as a filter, which can effectively filter out stray light in non-working bands to reduce optical noise, reduce difficulties for subsequent photoelectric module processing parts, and thus improve imaging quality. It can be understood that the surface of the photosensitive chip 11 facing the object side is the imaging surface.

[0061] In this embodiment, the focal length f of the infrared confocal lens 100 is 3.24 mm, and the aperture value F is 1.04.

[0062] It should be noted that, in this embodiment, the basic parameter table of each lens surface type, curvature radius, thickness, refractive index, dispersion coefficient and conic coefficient of the infrared confocal lens 100 is shown in Table 1:

[0063] Table 1

[0064]

[0065]

[0066] Furthermore, a design value of the aspheric coefficient in this embodiment is shown in Table 2 below:

[0067] Table 2

[0068]

[0069]

[0070] Figure 2 is a RAY FAN curve diagram of the visible light band of the infrared confocal lens 100 in this embodiment; Figure 3 is a RAY FAN curve diagram of the infrared band of the infrared confocal lens 100 in this embodiment; Figure 4 is a field curvature distortion diagram of the infrared confocal lens 100 in this embodiment.

[0071] It should be noted that Table 2 is a design value of the aspheric coefficient of the lens in the infrared confocal lens 100 described in this embodiment. The specific numerical value of the aspheric coefficient design value can be adjusted according to product requirements, and the present utility model does not impose any limitation on this.

[0072] The above description is only an exemplary embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An infrared confocal lens, characterized in that: The infrared confocal lens has an object side and an image side correspondingly arranged along the optical axis direction. The infrared confocal lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens and an image plane arranged in sequence from the object side to the image side, so that the total optical length of the infrared confocal lens is controlled within 22.5 mm, and the field of view angle can reach 157°. The optical focal power of the infrared confocal lens is φ, the optical focal power of the first lens is φ1, the optical focal power of the second lens is φ2, the optical focal power of the third lens is φ3, the optical focal power of the fourth lens is φ4, the optical focal power of the fifth lens is φ5, the optical focal power of the sixth lens is φ6, the optical focal power of the seventh lens is φ7, and the optical focal power of the eighth lens is φ8. The infrared confocal lens meets the following conditions: -0.67≤φ1 / φ≤-0.25; -0.60≤φ2 / φ≤-0.3; 0.1≤φ3 / φ≤0.35; 0.3≤φ4 / φ≤0.6; -0.55≤φ5 / φ≤0; -0.4≤φ6 / φ≤0.6; -0.8≤φ7 / φ≤-0.2; 0.3≤φ8 / φ≤0.7; Among them, the first lens is a glass spherical lens or a plastic aspherical lens, the second lens, the third lens, the seventh lens and the eighth lens are plastic aspherical lenses, and the fourth lens, the fifth lens and the sixth lens are glass spherical lenses.

2. The infrared confocal lens according to claim 1, characterized in that: The refractive index of the first lens is n1, 1.50≤n1≤1.60; The refractive index of the second lens is n2, 1.50≤n2≤1.75; The refractive index of the third lens is n3, 1.50≤n3≤1.70; The refractive index of the fourth lens is n4, 1.41≤n4≤1.70; The refractive index of the fifth lens is n5, 1.70≤n5≤1.90; The refractive index of the sixth lens is n6, 1.41≤n6≤1.70; The refractive index of the seventh lens is n7, 1.60≤n7≤1.75; The refractive index of the eighth lens is n8, 1.50≤n8≤1.

60.

3. The infrared confocal lens according to claim 1, characterized in that: The dispersion coefficient of the first lens is v1, 50.0≤v1≤65.0; The dispersion coefficient of the second lens is v2, 20.0≤v2≤65.0; The dispersion coefficient of the third lens is v3, 18.0≤v3≤25.0; The dispersion coefficient of the fourth lens is v4, 60.0≤v4≤95.0; The dispersion coefficient of the fifth lens is v5, 18.0≤v5≤30.0; The dispersion coefficient of the sixth lens is v6, 60.0≤v6≤95.0; The dispersion coefficient of the seventh lens is v7, 15.0≤v7≤25.0; The dispersion coefficient of the eighth lens is v8, 50.0≤v8≤60.

0.

4. The infrared confocal lens according to claim 1, characterized in that: The aperture value of the infrared confocal lens is F, 0.8≤F≤1.

1.

5. The infrared confocal lens according to claim 1, characterized in that: The focal length of the infrared confocal lens is f, the entrance pupil diameter of the infrared confocal lens is d, and 0.8≤f / d≤1.

1.

6. The infrared confocal lens according to claim 1, characterized in that: The back focus of the infrared confocal lens is BFL, the total length of the lens is TTL, and BFL / TTL≥0.

1.

7. The infrared confocal lens according to claim 6, characterized in that: The fifth lens and the sixth lens are cemented together.

8. The infrared confocal lens according to claim 1, characterized in that: The infrared confocal lens further includes an aperture, and the aperture is arranged between the second lens and the third lens.

9. The infrared confocal lens according to claim 1, characterized in that: The infrared confocal lens also includes a photosensitive chip, and the photosensitive chip is arranged on a side of the eighth lens close to the image side.

10. The infrared confocal lens according to claim 9, characterized in that: The infrared confocal lens also includes a protective glass, which is arranged between the eighth lens and the photosensitive chip.

Images