Gun sight infrared lens and lens module

Abstract

The invention belongs to the technical field of infrared optics, and discloses a gun sight infrared lens and a lens module. The lens comprises a first lens and a second lens which are sequentially arranged from the object side to the image side. The first lens and the second lens are meniscus lenses of which the convex surfaces face the object side; the focal power of the first lens and the focal power of the second lens are both positive. The air gap between the first lens and the second lens is 19.01 mm. According to the invention, the structure of the lens is compact by reasonably distributing the focal power, various aberrations are corrected by reasonably arranging the lenses, and the edge image quality is improved, so that the imaging quality is improved; the F number is 1, so that the lens can be clearly imaged under weak light, and the working performance is stable; according to the invention, only one germanium lens and one chalcogenide glass lens are adopted, so that the cost is low while the imaging quality is ensured.

Description

Technical Field

[0001] The present technology belongs to the field of infrared optical technology, and in particular relates to a gun aiming infrared lens and a lens module. Background Art

[0002] At present, infrared imaging technology has been widely used in military and civilian fields. Infrared thermal imaging rifle scopes mainly rely on the temperature difference of the target surface to detect hot targets. They can achieve all-weather observation, have strong anti-interference ability, and have a long range. They are suitable for low-light environments and adverse weather conditions. They have strong ability to discover and identify targets and are widely used in security reconnaissance, military confrontation and other fields.

[0003] In order to obtain higher image quality, existing rifle-type lenses generally use multiple lenses, and most of the lenses use high-cost germanium materials. Therefore, they cannot meet the needs of economical infrared systems with compact structure and high image quality. Summary of the invention

[0004] In order to solve the above problems, one purpose of the present invention is to provide a gun aiming infrared lens. The specific technical solution is as follows: A rifle aiming infrared scope, the lens comprising a first lens and a second lens arranged in sequence from the object side to the image side; the first lens and the second lens are both meniscus lenses with convex surfaces facing the object side; the optical focal lengths of the first lens and the second lens are both positive; and the air gap between the first lens and the second lens is 19.01 mm.

[0005] Furthermore, the center thickness of the first lens is 2.3 mm, the object side curvature radius is 20.43 mm, and the image side curvature radius is 22.87 mm; the center thickness of the second lens is 2.2 mm, the object side curvature radius is 15.80 mm, and the image side curvature radius is 18.98 mm.

[0006] Furthermore, the materials of the first lens and the second lens are germanium and chalcogenide glass respectively.

[0007] Furthermore, the object side surface of the first lens, the image side surface of the first lens, and the object side surface of the second lens are aspherical surfaces and satisfy the aspherical surface formula: Among them, Z is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height r along the optical axis; c=1 / R; R is the paraxial curvature fitting radius of the mirror; k is the cone coefficient; A, B, C, D, and E are high-order aspherical coefficients.

[0008] Furthermore, the image side surface of the second lens is a binary surface, which satisfies the aspheric surface formula and satisfies the expression equation of the binary surface in Zemax: M(B1ρ 2 +B2ρ4 ), where M is the diffraction order, B1 and B2 are the binary surface phase coefficients, and ρ is the normalized radius.

[0009] Further, M=1, B1=-13.18, B2=0.88, ρ=6.40.

[0010] Furthermore, a stop is provided on the image side surface of the first lens.

[0011] Furthermore, the lens has an operating band of 8 μm to 12 μm and an F number of 1.

[0012] Another object of the present invention is to provide a lens module, comprising the above-mentioned rifle-aiming infrared lens and a photosensitive element, wherein the photosensitive element is used to convert the optical image formed by the rifle-aiming infrared lens into an electrical signal.

[0013] Furthermore, the photosensitive element is a detector, the number of pixels of the detector is 384×288, and the pixel size is 12 μm.

[0014] Compared with the prior art, one or more of the above technical solutions can achieve at least one of the following beneficial effects: The present invention makes the lens structure compact by reasonably distributing the optical focal length, and corrects various aberrations by reasonably arranging the lenses, thereby improving the edge image quality and thus the imaging quality; the F number is 1, so that the lens can also form a clear image in weak light, and the working performance is stable; the present lens only uses one germanium lens and one chalcogenide glass lens, which ensures the imaging quality while having a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0016] Figure 1 This is a light path diagram of the gun aiming infrared lens of Example 1.

[0017] Figure 2 This is a diagram showing the lens composition of the rifle-aiming infrared lens of Example 1.

[0018] Figure 3 This is the spot diagram of the rifle-aiming infrared lens of Example 1.

[0019] Figure 4 This is the MTF diagram of the rifle-aiming infrared lens of Example 1.

[0020] Reference numerals: 1, first lens; 2, second lens; 3, protection window; 4, image plane. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It should be noted that the terms "first" and "second" are only used for the purpose of convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features.

[0022] For ease of understanding, the relevant terms involved are explained below.

[0023] The object side, with the lens as the boundary, the side where the object is located is the object side; the object side surface, the surface of the lens close to the object side is the object side; the image side, with the lens as the boundary, the side where the image of the object is located is the image side; the image side surface, the surface of the lens close to the image side is the image side; the meniscus lens, also known as a crescent lens, has one side that is concave and the other side that is convex.

[0024] Example 1 like Figure 1 As shown, this embodiment provides a gun aiming infrared lens. The lens includes a first lens 1 and a second lens 2 arranged in sequence from the object side to the image side; the first lens 1 is a meniscus lens with a convex surface facing the object side, and the second lens 2 is a meniscus lens with a convex surface facing the object side; the optical power of the first lens 1 and the second lens 2 are both positive.

[0025] As shown in Table 1, Figure 2 As shown, the center thickness of the first lens 1 is 2.3mm, the curvature radius of the object side S1 is 20.43mm, and the curvature radius of the image side S2 is 22.87mm; the center thickness of the second lens 2 is 2.2mm, the curvature radius of the object side S3 is 15.80mm, and the curvature radius of the image side S4 is 18.98mm. The air gap between the first lens 1 and the second lens 2 is 19.01mm. Among them, the object side S1 of the first lens 1 is the convex surface of the meniscus lens, and the image side S2 is the concave surface of the meniscus lens.

[0026] As a specific implementation, a stop is provided on the image-side surface S2 of the first lens 1 .

[0027] The materials of the first lens 1 and the second lens 2 are germanium and chalcogenide glass respectively. Compared with the prior art in which the lenses are all made of germanium, the present embodiment greatly reduces the cost.

[0028] Table 1 Parameters of each component As a specific implementation, as shown in Table 2, the object side surface S1 of the first lens 1, the image side surface S2 of the first lens, and the object side surface S3 of the second lens 2 are aspherical surfaces, and satisfy the aspherical surface formula: Among them, Z is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height r along the optical axis; c=1 / R; R is the paraxial curvature fitting radius of the mirror; k is the cone coefficient; A, B, C, D, and E are high-order aspherical coefficients.

[0029] Table 2 Aspheric surface data of lens The image side surface S4 of the second lens 2 is a binary surface, which satisfies the above aspheric surface formula and satisfies the expression equation of the binary surface in Zemax: M(B1ρ 2 +B2ρ 4 ), where M is the diffraction order, the diffraction order is 1, B1 and B2 are the binary surface phase coefficients, B1 = -13.18, B2 = 0.88, and the normalized radius ρ is 6.40.

[0030] Figure 3 , Figure 4 They are the spot diagram and MTF diagram of the lens. In the MTF diagram, the horizontal axis represents different spatial frequencies and the vertical axis represents the modulation degree. All fields of view represent the MTF curve of the meridian plane. It can be seen that the MTF is close to the diffraction limit, the root mean square diameter of the diffuse spot is smaller than the Airy disk diameter, and the image quality is good.

[0031] The infrared lens for aiming guns in this embodiment achieves the following optical parameters: Working band: 8μm~12μm; F number: 1; Resolution: 384×288, 12μm; Focal length: 25mm.

[0032] The lens of this embodiment has high imaging quality, compact structure and low cost through reasonable distribution of optical focal length, as well as design of optical materials, aspherical surfaces and diffraction surfaces. It is an economical lens that is particularly suitable for security reconnaissance, military confrontation and other fields.

[0033] This embodiment also provides a lens module, including the above-mentioned rifle aiming infrared lens and a photosensitive element, the photosensitive element is used to convert the optical image formed by the rifle aiming infrared lens into an electrical signal. The photosensitive element in this embodiment is a detector, the number of pixels of the detector is 384×288, and the pixel size is 12μm.

[0034] Obviously, the above embodiments are merely examples for clearly explaining the technical solutions of the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the protection of the claims of the present invention.

Claims

1. A rifle aiming infrared lens, characterized in that: The lens comprises a first lens and a second lens arranged in sequence from the object side to the image side; the first lens and the second lens are both meniscus lenses with convex surfaces facing the object side; the optical focal lengths of the first lens and the second lens are both positive; and the air gap between the first lens and the second lens is 19.01 mm.

2. The rifle aiming infrared lens according to claim 1, characterized in that: The center thickness of the first lens is 2.3 mm, the object side curvature radius is 20.43 mm, and the image side curvature radius is 22.87 mm; the center thickness of the second lens is 2.2 mm, the object side curvature radius is 15.80 mm, and the image side curvature radius is 18.98 mm.

3. The rifle aiming infrared lens according to claim 1, characterized in that: The materials of the first lens and the second lens are germanium and chalcogenide glass respectively.

4. The rifle aiming infrared lens according to claim 1, characterized in that: The object side surface of the first lens, the image side surface of the first lens, and the object side surface of the second lens are aspherical surfaces and satisfy the aspherical surface formula: Among them, Z is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height r along the optical axis; c=1 / R; R is the paraxial curvature fitting radius of the mirror; k is the cone coefficient; A, B, C, D, and E are high-order aspherical coefficients.

5. The rifle aiming infrared lens according to claim 4, characterized in that: The image side surface of the second lens is a binary surface, which satisfies the aspheric surface formula and satisfies the expression equation of the binary surface in Zemax: M(B1ρ 2 +B2ρ 4 ), where M is the diffraction order, B1 and B2 are the binary surface phase coefficients, and ρ is the normalized radius.

6. The rifle aiming infrared lens according to claim 5, characterized in that: M=1, B1=-13.18, B2=0.88, ρ=6.

40.

7. The rifle aiming infrared lens according to claim 1, characterized in that: An aperture is provided on the image side surface of the first lens.

8. The rifle aiming infrared lens according to any one of claims 1 to 7, characterized in that: The lens has an operating band of 8 μm to 12 μm and an F number of 1.

9. A lens module, characterized in that: It comprises the rifle-aiming infrared lens as described in any one of claims 1 to 8 and a photosensitive element, wherein the photosensitive element is used to convert the optical image formed by the rifle-aiming infrared lens into an electrical signal.

10. The lens module according to claim 9, characterized in that: The photosensitive element is a detector, the number of pixels of the detector is 384×288, and the pixel size is 12 μm.

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