A miniaturized and interchangeable mid-wave infrared mirror

Abstract

The present invention discloses a miniaturized interchangeable medium-wave infrared mirror. The medium-wave infrared mirror is composed of a first lens, a second lens, a third lens, a medium-wave detector aperture and an image plane in sequence from the object side to the imaging side. The first lens is composed of a meniscus-shaped germanium lens with a convex surface facing the object side. The present invention has the following advantages: the present invention has only three lenses, including two aspherical surfaces, with a simple structure and a small volume. At the same time, lenses of different focal lengths can share the last lens, so that the last lens can remain unchanged when the lens is exchanged, which can effectively reduce costs. In addition to having the advantages of high precision, high reliability, long distance, large range, good anti-interference ability, etc., the present invention can also meet the requirements of small F number miniaturization. At the same time, lenses of different focal lengths can share the last lens, so that the last lens can remain unchanged when the lens is exchanged, and can be well applied to the field of gas detection.

Description

Technical Field

[0001] The present invention relates to the field of optical lenses, and in particular to a miniaturized exchangeable medium-wave infrared lens. Background Art

[0002] Infrared imaging technology is increasingly being used as an effective means of gas detection in the petroleum, petrochemical, environmental protection, safety supervision, and power industries. It offers advantages such as high precision, high reliability, long-range detection, wide coverage, and excellent anti-interference capabilities. Compared to long-wave infrared imaging, medium-wave infrared imaging offers higher precision, longer range, and faster response times in gas detection, leading to its promising application prospects. This is why medium-wave infrared lenses, as a key component of this technology, have emerged.

[0003] Medium-wave infrared lenses for gas detection require a low F-number and miniaturization. In existing technical reports, Chinese patent CN113448063B discloses a medium-wave infrared lens with a large field of view and large relative aperture. This lens has a low F-number of 1.05, but uses four lenses, resulting in a large number of lenses and a large size. Chinese patent CN 210090811U discloses a compact, cooled, electric medium-wave infrared lens with an F-number of 2 and a focal length of 25°, totaling 90.4°. This lens is relatively large, and a single focal length cannot adapt to varying distances and environments. Summary of the Invention

[0004] The technical problem to be solved by the present invention is that, in existing technical reports, Chinese patent CN113448063B discloses a medium-wave infrared lens with a large field of view and large relative aperture. This lens has a small F-number of 1.05, but uses four lenses, resulting in a large number of lenses and a large size. Chinese patent CN 210090811 U discloses a compact medium-wave cooled infrared electric lens with an F-number of 2 and a focal length of 25, with a total length of 90.4. This lens is relatively large, and a single focal length cannot adapt to the needs of use at different distances and environments. Therefore, a miniaturized, interchangeable medium-wave infrared lens is provided to address the above problems.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a miniaturized interchangeable medium-wave infrared mirror, which is composed of a first lens, a second lens, a third lens, a medium-wave detector aperture and an image plane in sequence from the object side to the imaging side, characterized in that the first lens is composed of a meniscus-type germanium lens with a convex surface facing the object side, the second lens is composed of a meniscus-type germanium lens with a concave surface facing the object side, the third lens has positive refractive power and is composed of a meniscus-type silicon lens with a convex surface facing the object side, the first lens and the second lens each include an aspheric surface, and the rest are spherical surfaces, and without changing the third lens, the first lens and the second lens can be replaced to achieve switching between different focal lengths; lenses of different focal lengths can share the last lens, so that the last lens can remain unchanged when the lens is exchanged;

[0006] The focal lengths of the first lens, the second lens, and the third lens satisfy the following relationship:

[0007] |f1|>100;

[0008] |f2|>50;

[0009] 15<|f3|<75;

[0010] Wherein f1 is the focal length of the first lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens;

[0011] The f1 value is -445.9, the f2 value is 1017.6, the f3 value is 23.28, the focal length of the medium-wave infrared lens is 20mm, the F number is 1.2, the field of view angle is 27°×21.7°, and the total length is 60.

[0012] Furthermore, the first lens is used to converge light and improve aberration.

[0013] Furthermore, the second lens is used to converge light and improve aberration.

[0014] Furthermore, the third lens is used to converge light and compensate for the deviation of the image plane position of the system at different temperatures and different object distances.

[0015] Furthermore, the aspheric surface satisfies the following expression:

[0016]

[0017] Where: z is the lens sagittal height of the aspheric surface along the optical axis; c = 1 / R, R is the vertex radius of the aspheric surface, r is the semi-aperture of the lens perpendicular to the optical axis, k is the quadratic surface parameter, and A, B, C, and D are the aspheric coefficients.

[0018] Furthermore, the f1 value is 127.12, the f2 value is -57.71, the f3 value is 23.28, the focal length of the medium-wave infrared mirror is 50 mm, the F number is 1.2, the field of view angle is 11°×8.8°, and the total length is 110.

[0019] The present invention has the following advantages: the present invention has only three lenses, including two aspherical surfaces, with a simple structure and a small size. At the same time, lenses of different focal lengths can share the last lens, so that the last lens can be kept unchanged when the lens is exchanged, which can effectively reduce costs. In addition, the present invention has the advantages of high precision, high reliability, long distance, large range, good anti-interference ability, etc., and can also meet the requirements of small F number miniaturization. At the same time, lenses of different focal lengths can share the last lens, so that the last lens can be kept unchanged when the lens is exchanged, which can effectively reduce costs and can be well applied to the field of gas detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a light path diagram of the medium-wave infrared lens optical system of the preferred embodiment 1 of the present invention;

[0021] Figure 2 Schematic diagram of the MTF curve of the lens in preferred embodiment 1 of the present invention;

[0022] Figure 3 This is a light path diagram of the medium-wave infrared lens optical system of the preferred embodiment 2 of the present invention;

[0023] Figure 4 Schematic diagram of the MTF curve of the lens in preferred embodiment 2 of the present invention.

[0024] Explanation of reference numerals: 1. first lens; 2. second lens; 3. third lens; 4. medium-wavelength detector aperture; 5. image plane. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present invention are described clearly and completely below. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Many specific details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited by the specific embodiments disclosed below.

[0026] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The medium-wave infrared lens of the present invention will be described in detail below with reference to specific embodiments.

[0028] Please refer to Figure 1-Figure 4 The present invention discloses a miniaturized interchangeable medium-wave infrared mirror. The medium-wave infrared mirror is composed of a first lens, a second lens, a third lens, a medium-wave detector aperture, and an image plane in sequence from the object side to the imaging side. The first lens is composed of a meniscus-type germanium lens with a convex surface facing the object side, the second lens is composed of a meniscus-type germanium lens with a concave surface facing the object side, and the third lens has positive refractive power and is composed of a meniscus-type silicon lens with a convex surface facing the object side. The first lens and the second lens each include an aspheric surface, and the rest are spherical surfaces.

[0029] The first lens is used to converge and collect light and improve aberrations, the second lens is used to converge and collect light and improve aberrations, and the third lens is used to converge and collect light and compensate for the offset of the image plane position under different temperatures and object distances. Without changing the third lens, replacing the first lens and the second lens can achieve switching between different focal lengths.

[0030] Example 1, a miniaturized interchangeable medium-wave infrared lens, with a focal length of 20 mm, an F number of 1.2, a field of view of 27°×21.7°, and a total length of 60. Figure 1 As shown, from the object side to the image side, the lens includes, in order: first lens 1, second lens 2, third lens 3, medium-wavelength detector aperture 4, and image plane 5. First lens 1 is composed of a meniscus-shaped germanium lens with a convex surface facing the object side. Second lens 2 is composed of a meniscus-shaped germanium lens with a concave surface facing the object side. Third lens 3 has positive refractive power and is composed of a meniscus-shaped silicon lens with a convex surface facing the object side. The entire lens consists of three lenses, of which first lens 1 and second lens 2 each have an aspheric surface, while the remaining surfaces are spherical.

[0031] Preferably, the focal lengths of the three lenses satisfy the following relationship:

[0032] |f1|>100;

[0033] |f2|>50;

[0034] 15<|f3|<75;

[0035] Wherein, f1 is the focal length of the first lens 1 -445.9, f2 is the focal length of the second lens 2 1017.6, and f3 is the focal length of the third lens 3 23.28.

[0036] The MTF resolution curve of this embodiment is as follows: Figure 2 As shown, the horizontal axis represents the spatial frequency of line pairs / mm and the vertical axis represents the MTF value. Figure 2 It can be seen that this embodiment exhibits good contrast within a spatial frequency of 17 lp / mm in the central area, meeting the observation requirements of the human eye.

[0037] Table 1 shows the seven surfaces of the three lenses and the medium-wave detector aperture surface of the miniaturized interchangeable medium-wave infrared lens of Example 1. The curvature radius, lens center thickness, lens center distance, and lens refractive index thereof meet the following conditions:

[0038] Table 1

[0039] Surface number Face shape R (radius of curvature) D (center distance) Nd (refractive index) 1 spherical surface 60.4 6 2 Aspheric 53.5 9.99 4.03 3 spherical surface -19 6 4 Aspheric -23.37 10 4.03 5 spherical surface 50 5 6 spherical surface 400 10.51 3.43 7 aperture Infinity 0.4

[0040] The surfaces numbered 2 and 4 in the table are aspherical surfaces. Aspherical lenses satisfy the following formula:

[0041]

[0042] Where: z is the lens sag along the optical axis of the aspheric surface; c = 1 / R, R is the radius of the aspheric vertex, r is the semi-aperture of the lens perpendicular to the optical axis, k is the quadratic surface parameter, and A, B, C, and D are the aspheric coefficients. The aspheric surface parameters of this embodiment 1 are shown in Table 2:

[0043] Table 2

[0044] Surface number k (quadratic surface constant) A (4th order coefficient) B (6th order coefficient) C (8th order coefficient) D (8th order coefficient) 2 -0.28 4.48e-006 3.19e-008 -1.14e-010 5.02e-013 4 -0.74 -6.55e-006 -1.18e-008 9.34e-012 -5.97e-014

[0045] Example 2, a miniaturized interchangeable medium-wave infrared lens, with a focal length of 50 mm, an F number of 1.2, a field of view of 11°×8.8°, and a total length of 110. Figure 3 As shown, from the object side to the image side, the lens includes, in order: first lens 1, second lens 2, third lens 3, medium-wavelength detector aperture 4, and image plane 5. First lens 1 is composed of a meniscus-shaped germanium lens with a convex surface facing the object side. Second lens 2 is composed of a meniscus-shaped germanium lens with a concave surface facing the object side. Third lens 3 has positive refractive power and is composed of a meniscus-shaped silicon lens with a convex surface facing the object side. The entire lens consists of three lenses, of which first lens 1 and second lens 2 each have an aspheric surface, while the remaining surfaces are spherical.

[0046] Preferably, the focal lengths of the three lenses satisfy the following relationship:

[0047] |f1|>100;

[0048] |f2|>50;

[0049] 15<|f3|<75;

[0050] Wherein, f1 is the focal length of the first lens 1 127.12, f2 is the focal length of the second lens 2 -57.71, and f3 is the focal length of the third lens 3 23.28.

[0051] The MTF resolution curve of this embodiment is as follows: Figure 4As shown, the horizontal axis represents the spatial frequency of line pairs / mm and the vertical axis represents the MTF value. Figure 2 It can be seen that this embodiment exhibits good contrast within a spatial frequency of 17 lp / mm in the central area, meeting the observation requirements of the human eye.

[0052] Table 3 shows the seven surfaces of the three lenses and the medium-wave detector aperture surface of the miniaturized interchangeable medium-wave infrared lens of Example 2. The curvature radius, lens center thickness, lens center distance, and lens refractive index thereof meet the following conditions:

[0053] Table 3

[0054] Surface number Face shape R (radius of curvature) D (center distance) Nd (refractive index) 1 spherical surface 100.2 6 2 Aspheric 129.23 61.99 4.03 3 spherical surface -148.4 6 4 Aspheric -998 8 4.03 5 spherical surface 50 5 6 spherical surface 400 10.51 3.43 7 aperture Infinity 0.4

[0055] The surfaces numbered 2 and 4 in the table are aspherical surfaces.

[0056] The aspheric surface parameters in Example 2 are shown in Table 4:

[0057] Table 4

[0058] Surface number k (quadratic surface constant) A (4th order coefficient) B (6th order coefficient) C (8th order coefficient) D (8th order coefficient) 2 -6.64 4.3e-007 -6.04e-011 2.02e-014 -3.59e-018 4 88 1.81e-006 -1.86e-009 1.26e-011 -1.88e-014

[0059] It can be seen from Examples 1 and 2 that lenses with different focal lengths can share the third lens, so that the third lens can remain unchanged when the lenses are exchanged, which can effectively reduce costs and can be well applied in the field of gas detection.

[0060] The present invention not only has the advantages of high precision, high reliability, long distance, large range, good anti-interference ability, etc., but also meets the requirements of small F number and miniaturization. At the same time, lenses with different focal lengths can share the last lens, so that the last lens can be kept unchanged when the lens is exchanged, which can effectively reduce costs and can be well applied to the field of gas detection.

[0061] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all perspectives, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims, not the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be included within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0062] Other parts of the present invention not described in detail belong to the prior art and will not be described here in detail.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A miniaturized interchangeable medium-wave infrared mirror, which consists of a first lens, a second lens, a third lens, a medium-wave detector aperture, and an image plane in order from the object side to the imaging side, characterized in that: The first lens is composed of a meniscus-shaped germanium lens with a convex surface facing the object side, the second lens is composed of a meniscus-shaped germanium lens with a concave surface facing the object side, and the third lens has positive refractive power and is composed of a meniscus-shaped silicon lens with a convex surface facing the object side. The first lens and the second lens each include an aspheric surface, and the rest are spherical surfaces. Without changing the third lens, the first lens and the second lens can be replaced to achieve switching between different focal lengths. Lenses of different focal lengths can share the last lens, so that the last lens can remain unchanged when the lens is exchanged. The focal lengths of the first lens, the second lens, and the third lens are as follows: f1 is the focal length of the first lens, f2 is the focal length of the second lens, and f3 is the focal length of the third lens; The f1 value is -445.9mm, the f2 value is 1017.6mm, the f3 value is 23.28mm, the focal length of the medium-wave infrared lens is 20mm, the F number is 1.2mm, the field of view angle is 27°×21.7°, and the total length is 60mm; Or the f1 value is 127.12mm, the f2 value is -57.71mm, the f3 value is 23.28mm, the focal length of the medium-wave infrared lens is 50mm, the F number is 1.2mm, the field of view angle is 11°×8.8°, and the total length is 110mm.

2. A miniaturized interchangeable medium-wave infrared mirror as claimed in claim 1, characterized in that: The first lens is used to collect light and improve aberration.

3. The miniaturized interchangeable medium-wave infrared mirror according to claim 1, characterized in that: The second lens is used to collect light and improve aberration.

4. The miniaturized interchangeable medium-wave infrared mirror according to claim 1, characterized in that: The third lens is used to converge light and compensate for the deviation of the image plane position of the system at different temperatures and different object distances.

5. The miniaturized interchangeable medium-wave infrared mirror according to claim 1, characterized in that: The aspheric surface satisfies the following expression: Where: z is the lens sagittal height of the aspheric surface along the optical axis; c = 1 / R, R is the vertex radius of the aspheric surface, r is the semi-aperture of the lens perpendicular to the optical axis, k is the quadratic surface parameter, and A, B, C, and D are the aspheric coefficients.

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