Ultra-wide-angle long-wave infrared lens

Abstract

The utility model provides an ultra-wide-angle long-wave infrared lens, which comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged along an optical axis from an object side to an image side, the object side surface of the first lens is a convex surface, the image side surface of the first lens is a concave surface, and the first lens has negative diopter; the object side surface of the second lens is a convex surface, the image side surface of the second lens is a concave surface, and the second lens has positive diopter; the object side surface of the third lens is a concave surface, the image side surface of the third lens is a convex surface, and the third lens has negative diopter; the object side surface of the fourth lens is a concave surface, the image side surface of the fourth lens is a convex surface, and the fourth lens has a positive diopter. According to the utility model, the design of only four lenses is needed, the manufacturing cost is reduced, the overall size of the lens is small, and the lens is convenient to install and use.

Description

Technical Field

[0001] The utility model relates to the technical field of infrared lenses, in particular to an ultra-wide-angle long-wave infrared lens. Background Art

[0002] Most of the existing long-wave infrared lenses have one or more of the following defects: First, the common infrared single-focus lens usually has a small field of view, and when a large range needs to be observed, several lenses need to be spliced ​​to form an image; second, the common ultra-wide-angle lens generally has a large front port diameter, and the TTL is too long and the size is large, which is inconvenient for installation; third, it is difficult for common ultra-wide-angle lenses to take into account high-illuminance imaging, and the relative illumination of a large field of view is relatively low; fourth, the common infrared single-focus lens has a long minimum working distance that can be taken into account, and the resolution under close object distance conditions is low, and the image sharpness is poor. Utility Model Content

[0003] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an ultra-wide-angle long-wave infrared lens to solve the problems mentioned in the above background technology section.

[0004] The utility model is realized by the following technical solutions:

[0005] An ultra-wide-angle long-wave infrared lens comprises a first lens, a second lens, a third lens and a fourth lens which are arranged in sequence along an optical axis from an object side to an image side, wherein: the object side surface of the first lens is a convex surface, the image side surface of the first lens is a concave surface, and the first lens has a negative refractive power; the object side surface of the second lens is a convex surface, the image side surface of the second lens is a concave surface, and the second lens has a positive refractive power; the object side surface of the third lens is a concave surface, the image side surface of the third lens is a convex surface, and the third lens has a negative refractive power; the object side surface of the fourth lens is a concave surface, the image side surface of the fourth lens is a convex surface, and the fourth lens has a positive refractive power.

[0006] The beneficial effects of this embodiment are: only four lenses are needed, the manufacturing cost is reduced, the overall size of the lens is small, and it is easy to install and use.

[0007] Furthermore, the first lens to the fourth lens are all aspherical lenses.

[0008] The beneficial effect of this embodiment is that aspherical lenses are used to reduce manufacturing costs.

[0009] Furthermore, the total length of the lens is less than 15 mm, and the maximum field of view of the lens is greater than or equal to 190°.

[0010] The beneficial effects of this embodiment are: by reducing the size of the lens assembly, the lens volume is reduced, installation and use are convenient, and the lens has a larger maximum field of view and an ultra-wide-angle image capture capability.

[0011] Furthermore, the minimum working object distance of the lens optical system is 0.1 m, the aperture F of the lens is 1.0, and the relative illumination of the lens system is greater than 90%.

[0012] The beneficial effect of this embodiment is that the lens has clear resolution even at 0.1 mm and the image sharpness is high.

[0013] Furthermore, the lens satisfies the following relationship: nd1≥4, f1<0, wherein f1 is the focal length of the first lens, and nd1 is the refractive index of the first lens.

[0014] The beneficial effects of this embodiment are: satisfying the above range, correcting the off-axis higher-order aberrations of the lens, and increasing the field of view angle.

[0015] Furthermore, the lens satisfies the following relationship: f2<0, where f2 is the focal length of the second lens.

[0016] The beneficial effect of this embodiment is that satisfying the above range not only plays a role in correcting axial chromatic aberration, but also helps to reduce the front port diameter of the lens.

[0017] Furthermore, the lens satisfies the following relationship: f3<0, f4>0, wherein f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

[0018] The beneficial effects of this embodiment are: satisfying the range of the above formula is conducive to the correction of residual aberrations, the imaging quality of the lens is good, and the imaging quality from the center to the maximum field of view is relatively uniform. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the optical path principle diagram of the utility model.

[0020] Figure 2 This is the MTF curve diagram of the utility model.

[0021] Figure 3 This is a field curvature and distortion diagram of the utility model.

[0022] Figure 4 This is a relative illumination diagram of the present utility model.

[0023] The above drawings include the following reference numerals:

[0024] 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Protective sheet. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in 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. Therefore, the following detailed description of the embodiments of the utility model provided in the drawings is not intended to limit the scope of the utility model for which protection is claimed, but merely represents selected embodiments of the utility model.

[0026] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0027] Reference Figures 1 to 4 As shown,

[0028] An ultra-wide-angle long-wave infrared lens comprises a first lens, a second lens, a third lens and a fourth lens which are arranged in sequence along an optical axis from an object side to an image side, wherein: the object side surface of the first lens is a convex surface, the image side surface of the first lens is a concave surface, and the first lens has a negative refractive power; the object side surface of the second lens is a convex surface, the image side surface of the second lens is a concave surface, and the second lens has a positive refractive power; the object side surface of the third lens is a concave surface, the image side surface of the third lens is a convex surface, and the third lens has a negative refractive power; the object side surface of the fourth lens is a concave surface, the image side surface of the fourth lens is a convex surface, and the fourth lens has a positive refractive power.

[0029] The beneficial effects of this embodiment are: only four lenses are needed, the manufacturing cost is reduced, the overall size of the lens is small, and it is easy to install and use.

[0030] Furthermore, the first lens to the fourth lens are all aspherical lenses. The beneficial effect of this embodiment is that the aspherical lenses are used to reduce the manufacturing cost.

[0031] Furthermore, the total length of the lens is less than 15 mm, and the maximum field of view of the lens is greater than or equal to 190°. The beneficial effects of this embodiment are: by reducing the size of the lens assembly, the lens volume is reduced, installation and use are convenient, and the lens has a larger maximum field of view and has ultra-wide-angle image capture capability.

[0032] Furthermore, the minimum working object distance of the lens optical system is 0.1m, the aperture F of the lens is 1.0, and the relative illumination of the lens system is greater than 90%. The beneficial effect of this embodiment is that the lens has a clear resolution at 0.1mm and the image sharpness is high.

[0033] Furthermore, the lens satisfies the following relationship: nd1≥4, f1<0, wherein f1 is the focal length of the first lens, and nd1 is the refractive index of the first lens. The beneficial effect of this embodiment is that the above range is satisfied, and the off-axis high-order aberration of the lens is corrected to increase the field of view.

[0034] Further, the lens satisfies the following relationship: f2<0, where f2 is the focal length of the second lens. The beneficial effect of this embodiment is that satisfying the above range not only plays a role in correcting axial chromatic aberration, but also helps to reduce the front port diameter of the lens.

[0035] Furthermore, the lens satisfies the following relationship: f3<0, f4>0, wherein f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens. The beneficial effects of this embodiment are: satisfying the above range is conducive to the correction of residual aberrations, and the lens can be used with a 256*192@12um non-cooled detector, with high resolution within the entire target surface, and the imaging quality from the center to the edge is relatively consistent, and the imaging quality from the center to the maximum field of view is relatively uniform.

[0036] The present invention provides detailed optical data of Example 1 as shown in Table 1-1.

[0037] The conditional formula of the first embodiment is as follows:

[0038] Embodiment 1 f 1.3 BFL 4.64 BFL / f 3.5692308 y 1.92 y / f 1.4769231 TTL 15 BFL / TTL 0.3093333

[0039] Table 1-1 Detailed optical data

[0040]

[0041] Figure 2 This is the MTF graph. As can be seen from the graph, the MTF is greater than 0.3, indicating that the resolution of this example is high and the imaging quality is good.

[0042] Figure 3 This is a diagram of field curvature and distortion. As can be seen from the figure, the edge field distortion values ​​are all less than ±10%, the optical distortion is small under a large field of view, the imaging effect is good, and the imaging restoration is high

[0043] Figure 4 The relative illumination diagram is shown in Figure 1. As can be seen from the figure, the relative illumination of the lens is relatively large, and is greater than 90%. This enables the fixed-focus lens to have high illumination at working distances from 0.1m to infinity.

[0044] The above description is only the preferred implementation of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. An ultra-wide-angle long-wave infrared lens, characterized in that: The optical system comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence from the object side to the image side along the optical axis, wherein: The object side surface of the first lens is convex, the image side surface of the first lens is concave, and the first lens has negative refractive power; The object side surface of the second lens is convex, the image side surface of the second lens is concave, and the second lens has positive refractive power; The object side surface of the third lens is a concave surface, the image side surface of the third lens is a convex surface, and the third lens has a negative refractive power; The object side surface of the fourth lens is concave, the image side surface of the fourth lens is convex, and the fourth lens has positive refractive power.

2. The ultra-wide-angle long-wave infrared lens according to claim 1, characterized in that: The first lens to the fourth lens are all aspherical lenses.

3. The ultra-wide-angle long-wave infrared lens according to claim 1, characterized in that: The total length of the lens is less than 15 mm, and the maximum field of view of the lens is greater than or equal to 190°.

4. The ultra-wide-angle long-wave infrared lens according to claim 1, characterized in that: The shortest working object distance of the lens optical system is 0.1 m, the aperture F of the lens is 1.0, and the relative illumination of the lens system is greater than 90%.

5. The ultra-wide-angle long-wave infrared lens according to claim 1, characterized in that: The lens satisfies the following relationship: nd1≥4, f1<0, wherein f1 is the focal length of the first lens, and nd1 is the refractive index of the first lens.

6. The ultra-wide-angle long-wave infrared lens according to claim 1, characterized in that: The lens satisfies the following relationship: f2<0, where f2 is the focal length of the second lens.

7. The ultra-wide-angle long-wave infrared lens according to claim 1, characterized in that: The lens satisfies the following relationship: f3<0, f4>0, wherein f3 is the focal length of the third lens, and f4 is the focal length of the fourth lens.

Images