Double-view-field infrared lens and imaging system
By designing a dual field infrared lens including four lenses, the second lens moves back and forth along the optical axis direction, and optimizing the air spacing between the lenses and the thickness and curvature radius of the lenses, the problems of large number of lenses, high cost, large volume and small focal length are solved, and lenses with large focal lengths are realized while having a large focal length, reducing costs and volume, and improving imaging clarity.
Patent Information
- Application Number
- CN202411928338.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2025-03-11
AI Technical Summary
The existing dual-field infrared lenses have problems such as large number of lenses, high cost, large size and small focal length, which is difficult to meet the needs of modern military and civilian fields.
A dual field infrared lens is designed, including four lenses arranged in sequence along the optical axis transmission direction. The second lens can be reciprocated along the optical axis direction. By optimizing the air spacing between the lenses, the thickness and the radius of curvature of the lenses, the expansion of the focal length and the reduction of the number of lenses are achieved.
A dual-field infrared lens with a large focal length and a small number of lenses is realized, reducing cost and volume while improving imaging clarity.
Smart Images
Figure CN119596518A_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the field of infrared optical technology, and specifically relates to a dual-field-of-view infrared lens and imaging system. Background Art
[0002] Dual-field-of-view infrared lenses can realize the functions of large-field-of-view search and small-field-of-view precise identification. In modern military, dual-field-of-view infrared lenses are widely used in guidance, monitoring, infrared forward-looking systems, target detection and tracking, etc.; in civilian use, dual-field-of-view infrared lenses can be used in photography, space remote sensing and other fields.
[0003] Currently, dual-field-of-view infrared lenses face problems such as a large number of lenses, high cost, large size, and small focal length, which need to be solved urgently. Summary of the invention
[0004] Based on this, it is necessary to provide a dual-field-of-view infrared lens and imaging system with a large focal length and a small number of lenses.
[0005] The technical solution proposed in this application is: A dual-field-of-view infrared lens comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence along an optical axis transmission direction, wherein the second lens can move back and forth along the optical axis direction; and an air gap between the first lens and the second lens is 96.36-63.91 mm, an air gap between the second lens and the third lens is 26.14-58.59 mm, and an air gap between the third lens and the fourth lens is 53.55 mm.
[0006] Furthermore, the center thickness of the first lens is 12 mm, the object side curvature radius is 164 mm, and the image side curvature radius is 234.201 mm; the center thickness of the second lens is 3.5 mm, the object side curvature radius is -225.379 mm, and the image side curvature radius is 189.378 mm; the center thickness of the third lens is 8 mm, the object side curvature radius is 264.698 mm, and the image side curvature radius is -756.08 mm; the center thickness of the fourth lens is 6.8 mm, the object side curvature radius is 157.73 mm, and the image side curvature radius is 461.79 mm.
[0007] Further, the focal lengths are 60mm and 150mm; When the focal length is 150 mm, the air gap between the first lens and the second lens is 96.36 mm, and the air gap between the second lens and the third lens is 26.14 mm; When the focal length is 60 mm, the air space between the first lens and the second lens is 63.91 mm, and the air space between the second lens and the third lens is 58.59 mm.
[0008] Furthermore, the first lens, the second lens, the third lens and the fourth lens are made of germanium single crystal.
[0009] Furthermore, the first lens and the fourth lens are both meniscus positive lenses with convex surfaces facing the object side, the second lens is a double concave negative lens, and the third lens is a double convex positive lens.
[0010] Furthermore, the image side surface of the first lens, the image side surface of the second lens, the image side surface of the third lens, and the image side surface of the fourth lens are all 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.
[0011] Furthermore, the image side surface of the second lens satisfies the aspheric surface formula and satisfies the expression equation of the binary surface in Zemax: M(B 1 ρ 2 +B 2 ρ 4 + B 3 ρ 6 ), where M is the diffraction order, B 1 , B 2 , B 3 is the binary surface phase coefficient, ρ is the normalized radius. M is 1, B 1= -39.559, B 2= 10.121, B 3= -3.643,ρ=28.5.
[0012] Furthermore, the lens has an operating band of 8-12 μm and an F number of 1.
[0013] An imaging system comprises the dual-field-of-view infrared lens as described above and a detector for receiving images formed by the dual-field-of-view infrared lens.
[0014] Furthermore, the detector is a non-cooled detector, and the resolution of the detector is 1280×1024, and the pixel size is 12 μm.
[0015] The imaging system provided by the present application includes a dual-field infrared lens and a detector. The focal length of the lens is 60mm / 150mm, the working band is 8~12μm, and the F number is 1; the detector is a non-cooled detector, and the resolution of the detector is 1280×1024, and the pixel size is 12μm. At the same time, the lens has the characteristics of a small number of lenses and a large focal length, and the imaging is clear. BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The accompanying drawings are used to provide further understanding of the present application and constitute a part of the specification. They are used to explain the present application together with the embodiments of the present application and do not constitute a limitation of the present application.
[0017] Figure 1 A diagram of the lens composition of the imaging system provided for this application; Figure 2 The spot diagram of the lens provided for this application at a focal length of 60mm; Figure 3 MTF diagram of the lens provided for this application at a focal length of 60mm; Figure 4 The spot diagram of the lens provided for this application at a focal length of 150mm; Figure 5 MTF diagram of the lens provided for this application at a focal length of 150mm; Description of labels: 11. First lens; 12. Second lens; 13. Third lens; 14. Fourth lens; 21. Protection window; 22. Detector focal plane array. DETAILED DESCRIPTION
[0018] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0019] The present application provides an imaging system, including a dual-field-of-view infrared lens and a detector, the focal length of the lens is 60mm / 150mm, the working band is 8~12μm, and the F number is 1; the detector is a non-cooled detector, and the resolution of the detector is 1280×1024, and the pixel size is 12μm.
[0020] like Figure 1As shown, the dual-field-of-view infrared lens includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence along the transmission direction of the optical axis, and the second lens can move back and forth along the optical axis; and the air gap between the first lens and the second lens is 96.36~63.91mm, the air gap between the second lens and the third lens is 26.14~58.59mm, and the air gap between the third lens and the fourth lens is 53.55mm.
[0021] Specifically: When the focal length is 150 mm, the air gap between the first lens and the second lens is 96.36 mm, and the air gap between the second lens and the third lens is 26.14 mm; When the focal length is 60 mm, the air space between the first lens and the second lens is 63.91 mm, and the air space between the second lens and the third lens is 58.59 mm.
[0022] In one embodiment, the detector includes a protection window 21 and a detector focal plane array 22, such as Figure 1 As shown, the light beam passes through the first lens 11, the second lens 12, the third lens 13, and the fourth lens 14 from left to right, and then forms an image on the detector focal plane array 22 through the protective window 21. In practical applications, the air gap between the fourth lens 14 and the protective window 21 is 39.4 mm.
[0023] In one embodiment, the first lens and the fourth lens are both positive meniscus lenses with convex surfaces facing the object side, the second lens is a double concave negative lens, and the third lens is a double convex positive lens.
[0024] Furthermore, the center thickness of the first lens is 12 mm, the object side curvature radius is 164 mm, and the image side curvature radius is 234.201 mm; the center thickness of the second lens is 3.5 mm, the object side curvature radius is -225.379 mm, and the image side curvature radius is 189.378 mm; the center thickness of the third lens is 8 mm, the object side curvature radius is 264.698 mm, and the image side curvature radius is -756.08 mm; the center thickness of the fourth lens is 6.8 mm, the object side curvature radius is 157.73 mm, and the image side curvature radius is 461.79 mm.
[0025] It can be understood that the incident direction of the light is the object side, and the outgoing direction is the image side. Figure 1 For example, along the optical axis from left to right, the left side of the lens is the object side, and the right side is the image side. For example, the S1 surface of the first lens 11 is the object side surface, and the S2 surface is the image side surface. Other lenses are not described here.
[0026] In one embodiment, the materials of the first lens 11, the second lens 12, the third lens 13, and the fourth lens 14 are all germanium single crystal glass. The parameters of each lens can be found in Table 1.
[0027] Table 1 Lens parameters In one embodiment, the image side surface of the first lens, the image side surface of the second lens, the image side surface of the third lens, and the image side surface of the fourth lens are all 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.
[0028] Table 2 Aspheric coefficients In one embodiment, the image side surface of the second lens satisfies the aspheric surface formula and satisfies the expression equation of the binary surface in Zemax: M(B 1 ρ 2 +B 2 ρ 4 + B 3 ρ 6 ), where M is the diffraction order, B 1 , B 2 , B 3 is the binary surface phase coefficient, ρ is the normalized radius. M is 1, B 1= -39.559, B 2= 10.121, B 3= -3.643,ρ=28.5.
[0029] Figure 2 This is the spot diagram when the focal length is 150mm. Figure 3 This is the MTF graph when the focal length is 150mm; Figure 4 This is the spot diagram when the focal length is 60mm. Figure 5 This is the MTF diagram when the focal length is 60mm. In the MTF diagram, the horizontal axis represents different spatial frequencies and the vertical axis represents the modulation degree. It can be seen that the MTF is close to the diffraction limit, the RMS of the diffuse spot is smaller than the Airy disk diameter, and the image quality is good.
[0030] In summary, the imaging system provided by the present application includes a dual-field infrared lens and a detector. The focal length of the lens is 60mm / 150mm, the working band is 8~12μm, and the F number is 1; the detector is an uncooled detector, and the resolution of the detector is 1280×1024, and the pixel size is 12μm. At the same time, the lens has a small number of lenses, a large focal length, and clear imaging.
[0031] Although the embodiments of the present application have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the appended claims and their equivalents.
Claims
1. A dual-field-of-view infrared lens, characterized in that: It includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence along the transmission direction of the optical axis, and the second lens can move back and forth along the optical axis; and the air gap between the first lens and the second lens is 96.36~63.91mm, the air gap between the second lens and the third lens is 26.14~58.59mm, and the air gap between the third lens and the fourth lens is 53.55mm.
2. The dual-field-of-view infrared lens according to claim 1, characterized in that: The center thickness of the first lens is 12 mm, the object side curvature radius is 164 mm, and the image side curvature radius is 234.201 mm; the center thickness of the second lens is 3.5 mm, the object side curvature radius is -225.379 mm, and the image side curvature radius is 189.378 mm; the center thickness of the third lens is 8 mm, the object side curvature radius is 264.698 mm, and the image side curvature radius is -756.08 mm; the center thickness of the fourth lens is 6.8 mm, the object side curvature radius is 157.73 mm, and the image side curvature radius is 461.79 mm.
3. The dual-field-of-view infrared lens according to claim 1, characterized in that: The focal lengths are 60mm and 150mm; When the focal length is 150 mm, the air interval between the first lens and the second lens is 96.36 mm, and the air interval between the second lens and the third lens is 26.14 mm; When the focal length is 60 mm, the air space between the first lens and the second lens is 63.91 mm, and the air space between the second lens and the third lens is 58.59 mm.
4. The dual-field-of-view infrared lens according to claim 1, characterized in that: The first lens, the second lens, the third lens and the fourth lens are made of germanium single crystal.
5. The dual-field-of-view infrared lens according to claim 1, wherein: The first lens and the fourth lens are both positive meniscus lenses with convex surfaces facing the object side, the second lens is a double concave negative lens, and the third lens is a double convex positive lens.
6. The dual-field-of-view infrared lens according to claim 1, wherein: The image side surface of the first lens, the image side surface of the second lens, the image side surface of the third lens, and the image side surface of the fourth lens are all 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.
7. The dual-field-of-view infrared lens according to claim 6, characterized in that: The image side surface of the second lens satisfies the aspheric surface formula and satisfies the expression equation of the binary surface in Zemax: M(B1ρ 2 +B2ρ 4 + B3ρ 6 ), where M is the diffraction order, B1, B2, B3 are the binary surface phase coefficients, and ρ is the normalized radius; M is 1, B 1= -39.559, B 2= 10.121, B 3= -3.643,ρ=28.
5.
8. The dual-field-of-view infrared lens according to claim 1, wherein: The lens has an operating band of 8 to 12 μm and an F number of 1.
9. An imaging system, characterized in that: It comprises the dual-field-of-view infrared lens as claimed in any one of claims 1 to 8 and a detector for receiving images formed by the dual-field-of-view infrared lens.
10. The imaging system according to claim 9, characterized in that The detector is a non-cooling detector, and the resolution of the detector is 1280×1024, and the pixel size is 12 μm.