A middle wave refrigeration dual view field infrared lens and imaging device
By designing a mid-wave cooled dual-field infrared lens with a five-lens structure and employing movable lenses and diffraction surface technology, the problem of complex traditional lens structures has been solved, achieving a simple and efficient imaging effect and field-of-view switching capability.
Patent Information
- Application Number
- CN202411931649.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-26
- Publication Date
- 2025-10-24
- Estimated Expiration
- 2044-12-26
AI Technical Summary
Traditional dual-field infrared lenses have a large number of lenses, resulting in a complex structure that makes it difficult to achieve simple and efficient imaging.
Design a mid-wave cooled dual-field infrared lens with a five-lens structure, including a meniscus positive lens with its convex surface facing the object side, a biconcave lens, and a biconvex lens. The second lens is movable to switch the field of view, and the fifth lens is a diffractive surface, matched with a 320×256 pixel cooled detector.
It achieves a simple lens structure, clear imaging, applicable spectral range of 3.2~3.5μm, focal length of 18mm and 54mm, F number of 1.5, and can be matched with a cooled detector with a resolution of 320×256 and 30μm, and has the ability to switch between large and small field of view.
Smart Images
Figure CN119805706B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of infrared optical equipment, and particularly relates to a middle-wave refrigeration dual-view field infrared lens and an imaging device. BACKGROUND
[0002] The dual-view field lens has two focal lengths and two view fields as its name implies. The view field angle is relatively large at a small focal length, and it is easy to find a target. The view field angle is relatively small at a large focal length, and it is easy to track a target. The dual-view field infrared lens can be used for gas detection, such as combustible gas or toxic gas, in cooperation with a middle-wave refrigeration gas detection instrument. However, the traditional dual-view field infrared lens has a large number of lenses. SUMMARY
[0003] Based on this, the application provides a middle-wave refrigeration dual-view field infrared lens and an imaging device with a simple structure.
[0004] The technical scheme provided in the application is as follows:
[0005] A middle-wave refrigeration dual-view field infrared lens comprises first, second, third, fourth and fifth lenses arranged in sequence along the transmission direction of the optical axis. The first lens is a meniscus positive lens with the convex surface facing the object side, the second lens is a double-concave lens, the third and fifth lenses are double-convex lenses, and the fourth lens is a meniscus positive lens with the convex surface facing the image side.
[0006] The second lens is reciprocally movable along the optical axis direction, the air gap between the first lens and the second lens is 15-27.93 mm, the air gap between the second lens and the third lens is 5-17.93 mm, the air gap between the third lens and the fourth lens is 25 mm, and the air gap between the fourth lens and the fifth lens is 24.92 mm.
[0007] Further, the central thickness of the first lens is 6 mm, the curvature radius of the object side surface is 56.99 mm, and the curvature radius of the image side surface is 101.086 mm; the central thickness of the second lens is 1.8 mm, the curvature radius of the object side surface is -62.699 mm, and the curvature radius of the image side surface is 72.82; the central thickness of the third lens is 5.5 mm, the curvature radius of the object side surface is 74.949 mm, and the curvature radius of the image side surface is -45.264 mm; the central thickness of the fourth lens is 4.6 mm, the curvature radius of the object side surface is -10.937 mm, and the curvature radius of the image side surface is -13.12 mm; and the central thickness of the fifth lens is 5.5 mm, the curvature radius of the object side surface is 586.299 mm, and the curvature radius of the image side surface is -52.319 mm.
[0008] Further, the first lens and the lens satisfy the following condition: f1 / f<3, wherein f1 is an effective focal length of the first lens, and f is an effective focal length of the lens.
[0009] Further, the fifth lens and the lens satisfy the following condition: 0.3
[0010] Further, the lens has an applicable spectral range of 3.2~3.5μm, a focal length of 18mm and 54mm, and an F number of 1.5.
[0011] When the focal length of the lens is 18mm, the air gap between the first lens and the second lens is 15mm, and the air gap between the second lens and the third lens is 17.93mm; when the focal length of the lens is 54mm, the air gap between the first lens and the second lens is 27.93mm, and the air gap between the second lens and the third lens is 5mm.
[0012] Further, the lens adopts a double imaging design.
[0013] Further, the object side surface of the fifth lens is a diffractive surface, and the diffractive surface satisfies the following expression:
[0014] ;
[0015] ;
[0016] wherein, is a phase of the diffractive surface, r n is a planning radius of the diffractive surface, r is a height in a direction perpendicular to an optical axis, and A1 and A2 are phase coefficients of the diffractive surface.
[0017] An imaging device includes the mid-wave refrigeration dual-view field infrared lens and a detector receiving an image formed by the lens.
[0018] Further, the detector has a pixel number of 320x256 and a pixel size of 30μm.
[0019] The lens structure provided by the present application is simple, has a large target surface, and forms a clear image, and can be matched with a resolution of 320x256, 30μm refrigeration type detector. BRIEF DESCRIPTION OF DRAWINGS
[0020] The accompanying drawings are included to provide a further understanding of the present application, and constitute a part of the specification, illustrate the present application together with the embodiments thereof, and explain the present application, but do not limit the present application.
[0021] Figure 1 A structural schematic diagram of an imaging device provided by an embodiment of the present application when the focal length of the lens is 18mm;
[0022] Figure 2 A structural schematic diagram of an imaging device provided by an embodiment of the present application when the focal length of the lens is 54mm;
[0023] Figure 3 An MTF diagram of a mid-wave refrigeration dual-view infrared lens provided by an embodiment of the present application when the focal length is 18mm;
[0024] Figure 4 A point column diagram of a mid-wave refrigeration dual-view infrared lens provided by an embodiment of the present application when the focal length is 18mm;
[0025] Figure 5 An MTF diagram of a mid-wave refrigeration dual-view infrared lens provided by an embodiment of the present application when the focal length is 54mm;
[0026] Figure 6 A point column diagram of a mid-wave refrigeration dual-view infrared lens provided by an embodiment of the present application when the focal length is 54mm.
[0027] Label explanation:
[0028] 11, first lens; 12, second lens; 13, third lens; 14, fourth lens; 15, fifth lens; 21, protective window; 22, optical filter; 23, diaphragm; 24, detector focal plane array. DETAILED DESCRIPTION
[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.
[0030] An imaging device provided by an embodiment of the present application includes a mid-wave refrigeration dual-view infrared lens and a detector receiving the image formed by the lens. The focal length of the lens is 18mm and 54mm, the applicable spectral range is 3.2~3.5μm, and the F number is 1.5. The detector is a refrigeration type detector, and the number of pixels of the detector is 320×256, and the pixel size is 30μm.
[0031] Please refer to Figure 1The lens comprises, in sequence along the transmission direction of the optical axis, a first lens, a second lens, a third lens, a fourth lens and a fifth lens. The first lens is a convex-to-object-side meniscus positive lens, the second lens is a double-concave lens, the third lens and the fifth lens are double-convex lenses, and the fourth lens is a convex-to-image-side meniscus positive lens. Further, the detector comprises, in sequence, a protective window, a filter and a detector focal plane array, so that Figure 1 For example, the light beam passes through the first lens, the second lens, the third lens, the fourth lens and the fifth lens in sequence from left to right, and then forms an image on the detector focal plane array through the protective window and the filter.
[0032] In one embodiment, the detector further comprises a diaphragm, which is arranged between the filter and the detector focal plane array.
[0033] In one embodiment, the lens adopts a double-imaging design.
[0034] As shown in Table 1, as an example, the air gap between the first lens and the second lens is 15-27.93 mm, the air gap between the second lens and the third lens is 5-17.93 mm, the air gap between the third lens and the fourth lens is 25 mm, the air gap between the fourth lens and the fifth lens is 24.92 mm, the air gap between the fifth lens and the protective window is 10 mm, the air gap between the protective window and the filter is 2.4 mm, the air gap between the filter and the diaphragm is 0.25 mm, and the air gap between the diaphragm and the detector focal plane array is 19.8 mm.
[0035] Therefore, the second lens can reciprocate along the optical axis direction, thereby realizing switching between a large field of view and a small field of view. Specifically, when the lens is in the large field of view, the focal length of the lens is 18 mm, the air gap between the first lens and the second lens is 15 mm, and the air gap between the second lens and the third lens is 17.93 mm; when the lens is in the small field of view, the focal length of the lens is 54 mm, the air gap between the first lens and the second lens is 27.93 mm, and the air gap between the second lens and the third lens is 5 mm. It can be understood that the air gap is the air gap on the optical axis.
[0036] In one embodiment, the first lens has a center thickness of 6 mm, an object-side surface radius of curvature of 56.99 mm, and an image-side surface radius of curvature of 101.086 mm; the second lens has a center thickness of 1.8 mm, an object-side surface radius of curvature of -62.699 mm, and an image-side surface radius of curvature of 72.82; the third lens has a center thickness of 5.5 mm, an object-side surface radius of curvature of 74.949 mm, and an image-side surface radius of curvature of -45.264 mm; the fourth lens has a center thickness of 4.6 mm, an object-side surface radius of curvature of -10.937 mm, and an image-side surface radius of curvature of -13.12 mm; and the fifth lens has a center thickness of 5.5 mm, an object-side surface radius of curvature of 586.299 mm, and an image-side surface radius of curvature of -52.319 mm.
[0037] It can be understood that, in the embodiment shown in the figure, the optical axis transmission direction is 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 is the object side surface, and the S2 surface is the image side surface. The other lenses are not described in detail. Figure 1
[0038] In one embodiment, the first lens, the fifth lens, and the lens satisfy the following conditions:
[0039] f1 / f < 3 and 0.3 < f5 / f < 1.3; wherein f is the effective focal length of the lens, f1 is the effective focal length of the first lens, and f5 is the effective focal length of the fifth lens.
[0040] Table 1 Component parameters
[0041]
[0042] In combination with Table 1, it should be noted that the lenses described above are all made of domestic optical materials.
[0043] As shown in Table 1, the image side surface of the first lens and the third lens, and the object side surface of the second lens, the fourth lens, and the fifth lens are all aspherical surfaces, and all the aspherical surfaces satisfy the aspherical surface formula:
[0044]
[0045] wherein z represents the distance of the curve from the curve vertex in the optical axis direction, c represents the curvature of the curve vertex, K represents the quadratic curve coefficient, h represents the distance of the optical axis to the curve, B, C, D, E, and F represent the fourth-order, sixth-order, eighth-order, tenth-order, and twelfth-order curve coefficients, respectively. At the same time, the aspherical surface data of each lens is shown in Table 2.
[0046] Table 2 Aspherical surface data
[0047]
[0048] In one embodiment, the object side surface of the fifth lens is a diffractive surface, and the diffractive surface satisfies the following expression:
[0049] ;
[0050] ;
[0051] wherein, is the phase of the diffractive surface, r n is the planning radius of the diffractive surface, r is the height in the direction perpendicular to the optical axis, A1 and A2 are the phase coefficients of the diffractive surface.
[0052] The parameters of the above diffractive surface are shown in Table 3.
[0053] Table 3 Parameters of the diffractive surface
[0054]
[0055] Figure 3 and Figure 4 are the MTF diagram and the point column diagram of the mid-wave refrigeration dual-view infrared lens when the focal length is 18mm, respectively; Figure 5 and Figure 6 are the MTF diagram and the point column diagram of the mid-wave refrigeration dual-view infrared lens when the focal length is 54mm, respectively. In the MTF diagram, the horizontal axis represents different spatial frequencies, and the vertical axis represents the modulation degree. It can be seen from the drawings that the lens corrects various aberrations of each waveband, so that the central and edge fields have sufficient resolution.
[0056] In summary, the working waveband of the mid-wave refrigeration dual-view infrared lens provided in the application is 3.2~3.5μm; the focal length f=18mm and 54mm; and the F number is 1.5. The lens structure provided in the application is simple, has a large target surface, and has clear imaging, and can match a resolution of 320x256 and a 30μm refrigeration type detector.
[0057] Although the embodiments of the application have been shown and described, it can be understood by those of ordinary skill in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the application, and the scope of the application is defined by the appended claims and their equivalents.
Claims
1. A medium wave refrigeration dual view infrared lens characterized in that, The first lens, the second lens, the third lens, the fourth lens and the fifth lens are sequentially arranged along the optical axis direction; the first lens is a convex-to-object-side meniscus positive lens, the second lens is a double-concave lens, the third lens and the fifth lens are both double-convex lenses, and the fourth lens is a convex-to-image-side meniscus positive lens; The second lens is reciprocally movable along the optical axis direction, the air gap between the first lens and the second lens is 15-27.93 mm, the air gap between the second lens and the third lens is 5-17.93 mm, the air gap between the third lens and the fourth lens is 25 mm, and the air gap between the fourth lens and the fifth lens is 24.92 mm.
2. The mid-wave refrigerated dual view infrared lens of claim 1, wherein, The center thickness of the first lens is 6 mm, the object-side surface curvature radius is 56.99 mm, and the image-side surface curvature radius is 101.086 mm; the center thickness of the second lens is 1.8 mm, the object-side surface curvature radius is -62.699 mm, and the image-side surface curvature radius is 72.82 mm; the center thickness of the third lens is 5.5 mm, the object-side surface curvature radius is 74.949 mm, and the image-side surface curvature radius is -45.264 mm; the center thickness of the fourth lens is 4.6 mm, the object-side surface curvature radius is -10.937 mm, and the image-side surface curvature radius is -13.12 mm; and the center thickness of the fifth lens is 5.5 mm, the object-side surface curvature radius is 586.299 mm, and the image-side surface curvature radius is -52.319 mm.
3. The medium-coolant temperature dual-view infrared lens of claim 1, wherein, The first lens and the lens satisfy the following condition: f1 / f<3, wherein f1 is the effective focal length of the first lens, and f is the effective focal length of the lens.
4. The medium-coolant temperature dual-view infrared lens of claim 1, wherein, The fifth lens and the lens satisfy the following condition: 0.3 5. The medium-coolant temperature dual-view infrared lens of claim 1, wherein, The applicable spectral range of the lens is 3.2-3.5 μm, the focal length of the lens is 18 mm and 54 mm, and the F number is 1.
5. When the focal length of the lens is 18 mm, the air gap between the first lens and the second lens is 15 mm, and the air gap between the second lens and the third lens is 17.93 mm; when the focal length of the lens is 54 mm, the air gap between the first lens and the second lens is 27.93 mm, and the air gap between the second lens and the third lens is 5 mm.
6. The medium-coolant temperature dual-view infrared lens of claim 1, wherein, The lens adopts a double-imaging design.
7. The medium-coolant temperature dual-view infrared lens of claim 1, wherein, The object-side surface of the fifth lens is a diffractive surface, and the diffractive surface satisfies the following expression: ； ； wherein is the phase of the diffractive surface, r n is the design radius of the diffractive surface, r is the height in the perpendicular direction to the optical axis, and A1, A2 are phase coefficients of the diffractive surface.
8. An image forming apparatus characterized by comprising: The application also discloses a detector receiving the image formed by the lens.
9. The imaging apparatus according to claim 8, wherein The number of pixels of the detector is 320x256, and the pixel size is 30 μm.
Citation Information
Patent Citations
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