CN219997399U - Small-size athermalization infrared objective lens - Google Patents
Small-size athermalization infrared objective lens Download PDFInfo
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- CN219997399U CN219997399U CN202321505294.4U CN202321505294U CN219997399U CN 219997399 U CN219997399 U CN 219997399U CN 202321505294 U CN202321505294 U CN 202321505294U CN 219997399 U CN219997399 U CN 219997399U
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- 239000011521 glass Substances 0.000 claims abstract description 5
- 230000005499 meniscus Effects 0.000 claims description 11
- 230000014509 gene expression Effects 0.000 claims description 6
- 230000003287 optical effect Effects 0.000 abstract description 36
- 238000003384 imaging method Methods 0.000 description 7
- 238000012546 transfer Methods 0.000 description 6
- 101100117236 Drosophila melanogaster speck gene Proteins 0.000 description 3
- 238000013461 design Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000013041 optical simulation Methods 0.000 description 3
- 239000005387 chalcogenide glass Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
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Abstract
The utility model discloses a small-size athermalized infrared objective lens, which comprises a first lens, a second lens, a third lens and detector protection glass, wherein the first lens, the second lens, the third lens and the detector protection glass are sequentially arranged on an axis; the first object side surface of the first lens is a convex surface, and the first image side surface of the first lens is a concave surface; the second object side surface of the second lens is a concave surface, and the second image side surface of the second lens is a convex surface; the third object side surface of the third lens is a concave surface, and the third image side surface of the third lens is a convex surface. The utility model realizes excellent performances of small size, high resolution, heat eliminating difference and the like by adopting the optical lens formed by three lenses, mutually combining different lenses and reasonably distributing focal power, and has the advantages of simple structure, short size and strong practicability as a whole, and the ratio of optical length to focal length is 1.36.
Description
Technical Field
The utility model relates to the technical field of optics, in particular to a small-size athermalized infrared objective lens.
Background
The long-wave infrared is widely applied to the fields of military, investigation and the like by the technical characteristics, and a large number of long-wave infrared temperature measuring systems are applied in epidemic situations. Due to the characteristics of the long-wave infrared band, in optical design, widely used optical materials include germanium, chalcogenide glass and other materials. The materials have the problem of larger thermal expansion coefficient under high and low temperature environments, so that in order to ensure that the infrared optical objective lens has better imaging quality under different temperature environments, an optical athermal design is required.
In the athermalization infrared optical system, in order to obtain better imaging quality under different temperature conditions of high temperature and low temperature, the length of the optical system is usually more than 2 times of the focal length value, but in certain specific application scenes, the length index requirement on the optical system is higher, so that in certain application scenes with strict size requirements, such as 640 x 512 aiming at long-wave non-refrigeration type, a pixel 12 μm focal plane detector, how to ensure that the optical system has shorter optical length and high resolution imaging and realize athermalization design becomes a technical problem which needs to be solved urgently.
Disclosure of Invention
The utility model provides a small-sized athermalized infrared objective lens which can overcome the defects in the prior art.
In order to achieve the technical purpose, the technical scheme of the utility model is realized as follows:
a small-size athermalized infrared objective lens comprises a first lens, a second lens, a third lens and detector protection glass which are sequentially arranged on an axis; the first object side surface of the first lens is a convex surface, and the first image side surface of the first lens is a concave surface; the second object side surface of the second lens is a concave surface, and the second image side surface of the second lens is a convex surface; the third object side surface of the third lens is a concave surface, and the third image side surface of the third lens is a convex surface.
Further, the first lens is a meniscus negative lens, and the diopter of the first lens is negative.
Further, the second lens is a meniscus positive lens, and the diopter of the second lens is positive.
Further, a diaphragm is arranged on the second object side surface of the second lens.
Further, the third lens is a meniscus positive lens.
Further, the first lens, the second lens and the third lens are respectively provided with an aspheric surface, and the second image side surface of the second lens adopts an aspheric superposition diffraction surface.
Further, the first lens and the second lens satisfy the following expression:
1＜f 1，2 /f＜3
wherein f 1，2 Is the combined focal length of the first lens and the second lens, and f represents the focal length of the whole lens group.
Further, the first lens, the second lens and the third lens are all relatively fixed.
The utility model has the beneficial effects that: the utility model realizes excellent performances of small size, high resolution, heat eliminating difference and the like by adopting the optical lens formed by three lenses, mutually combining different lenses and reasonably distributing focal power, and has the advantages of simple structure, short size and strong practicability as a whole, and the ratio of optical length to focal length is 1.36.
Drawings
In order to more clearly illustrate the embodiments of the present utility model or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present utility model, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of the optical structure of a small-sized athermalized infrared objective according to an embodiment of the present utility model;
FIG. 2 is a graph of the transfer function of a small-sized athermalized infrared objective at 20℃according to an embodiment of the present utility model;
FIG. 3 is a plot of the diffuse speckle of a small-sized athermalized infrared objective at 20 ℃ according to an embodiment of the present utility model;
FIG. 4 is a graph of curvature of field and distortion of a small-sized athermalized infrared objective at 20℃according to an embodiment of the present utility model;
FIG. 5 is a graph of the transfer function of a small-sized athermalized infrared objective at-40 ℃ according to an embodiment of the present utility model;
FIG. 6 is a plot of the diffuse speckle at-40 ℃ for a small-sized athermalized infrared objective according to an embodiment of the present utility model;
FIG. 7 is a graph of field curvature and distortion of a small-sized athermalized infrared objective at-40 ℃ according to an embodiment of the present utility model;
FIG. 8 is a graph of the transfer function of a small-sized athermalized infrared objective at 60 ℃ according to an embodiment of the present utility model;
FIG. 9 is a plot of the diffuse speckle at 60 ℃ for a small-sized athermalized infrared objective according to an embodiment of the present utility model;
FIG. 10 is a graph of curvature of field and distortion at 60℃for a small-sized athermalized infrared objective according to an embodiment of the present utility model;
in the figure: 1. a first lens; 2. a second lens; 3. a third lens; 4. a detector protection glass; 5. a detector focal plane; 6. a diaphragm; 11. an object side I; 12. an image side I; 21. an object side II; 22. an image side II; 31. an object side three; 32. and an image side three.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. All other embodiments, which are derived by a person skilled in the art based on the embodiments of the utility model, fall within the scope of protection of the utility model.
As shown in fig. 1, a small-sized athermalized infrared objective lens according to an embodiment of the present utility model sequentially includes, from an object side to an image side: a first lens 1, a second lens 2, and a third lens 3.
In the embodiment, the first object-side surface 11 of the first lens element 1 is convex, the first image-side surface 12 is concave, and the optical power thereof is negative; the first lens 1 is a meniscus negative lens, which can effectively shrink light and reduce the size of the lens.
In the embodiment, the second object-side surface 21 of the second lens element 2 is concave, the second image-side surface 22 is convex, and the focal power thereof is positive; the second lens 2 is a meniscus positive lens, and can effectively correct curvature of field. And the diaphragm 8 of the optical system is located at the object plane of the second lens.
In the embodiment, the third object-side surface 31 of the third lens element 3 is concave, the third image-side surface 32 is convex, and the focal power thereof is positive; the third lens 3 is a positive lens, so that the influence of temperature change on the optical system can be effectively eliminated, and the environmental adaptability of the optical system is improved.
In the embodiment, the first lens element 1, the second lens element 2 and the third lens element 3 each have a higher order aspheric surface, and the image-side surface of the second lens element 2 has an aspheric superimposed diffraction surface.
In the embodiment, the first lens 1 and the second lens 2 satisfy the following expression:
1＜f 1，2 /f＜3
wherein f 1，2 Is the combined focal length of the first lens and the second lens; f represents the focal length of the entire lens group.
In order to facilitate understanding of the above technical solutions of the present utility model, the following describes the above technical solutions of the present utility model in detail by a specific usage manner.
When the utility model is particularly used, the small-size athermalized infrared objective lens sequentially comprises the following components from an object side to an image side along an optical axis: a first lens 1 having negative optical power, a second lens 2 having positive optical power, and a third lens 3 having positive optical power.
In the embodiment of the utility model, the first lens 1 is a meniscus negative lens, so that light rays can be effectively contracted, and the size of the lens is reduced.
The second lens 2 is a meniscus positive lens, and can effectively correct curvature of field. And the diaphragm 6 of the optical system is located on the object side of the second lens.
The third lens 3 is a meniscus positive lens, so that the influence of temperature change on the optical system can be effectively eliminated, and the environmental adaptability of the optical system can be improved.
In order to improve the optical performance of the whole lens, certain lenses need to be specially designed to meet specific expressions so as to achieve better imaging effect. In the present embodiment, f 1，2 =15.54 mm, f=10.2 mm. The first lens 1 and the second lens 2 satisfy the following expression:
1＜f 1，2 /f＜3
wherein f 1，2 Is the combined focal length of the first lens 1 and the second lens 2; f represents the focal length of the entire lens group.
After the above expression is satisfied, the small-size requirement of the entire optical system can be ensured.
Specifically, in this embodiment, for a non-refrigerated focal plane detector of 640×512, the pixel size 12 μm, the focal length f of the present optical system is designed: 10.2mm, F number: 1.1, field of view: 43.6 x 35.4. The three total image-side lengths of the first lens element 1 from the object-side surface to the third lens element are 13.9mm.
More specifically, in order to improve the image quality and to improve the influence of temperature changes on the image quality, the first lens 1, the second lens 2, and the third lens 3 each have a higher order aspherical surface. The second lens 2 has an aspherical superimposed diffraction plane on the second image side.
In the implementation, the diffraction surface is prevented from being added on the chalcogenide glass, the asphericity is smaller than 0.7mm, the optical processing and manufacturing are easy, the precision is easy to ensure, and the production cost is reduced to the greatest extent.
Table 1 lists the aspherical coefficients of the first object-side surface 11, the first image-side surface 12, the second image-side surface 22 of the second lens element 2, and the third object-side surface 31 of the third lens element 3.
Table 1 aspherical coefficients of object side one 11, image side one 12, image side two 22, object side three 31
| Surface of the body | K | A | B | C | D |
| Object side one 11 | 0 | 1.77447e-04 | -1.06741e-06 | -1.31276e-08 | -2.66093e-09 |
| Image side one 12 | 0 | 1.857176e-04 | -7.26244e-06 | -1.85809e-07 | -4.58713e-008 |
| Image side two 22 | 0 | -9.02736e-005 | -1.07978e-06 | -3.17379e-08 | 2.54473e-010 |
| Three object side surfaces 31 | 0 | 1.09569e-04 | -1.80091e-07 | 1.74163e-08 | -1.34707e-09 |
The even aspherical equation is defined as follows:
table 2 lists the diffraction plane coefficients of the second lens 2 surface image side two 22.
Table 2 diffraction plane coefficients of image side two 22
| Surface of the body | Diffraction orders | Center wavelength (mum) | C1 | C2 |
| 22 | 1 | 10 | -7.92539e-04 | -3.69798e-06 |
Wherein C1 and C2 are the 2 nd order and 4 th order coefficients of the diffraction surface respectively.
Because the embodiment adopts four aspheric surfaces and one diffraction surface, good imaging quality is achieved, manufacturability is good, and the effects of reducing cost and simplifying lenses are achieved.
Fig. 2 to 4 are graphs of imaging optical simulation data of the small-sized athermalized infrared objective lens of the present utility model at 20 ℃, wherein fig. 2 is a graph of optical transfer function (MTF), the horizontal axis is logarithmic per millimeter line (lp/mm), the vertical axis is contrast value, fig. 3 is a dot column graph, and fig. 4 is a graph of field curvature and distortion. From the graph curves of fig. 2 to 4, it can be seen that the MTF, the root mean square value of the diffuse speck, and the field curvature and distortion at 20 ℃ are all within the standard range.
Fig. 5 to 7 are graphs of image optical simulation data of the small-sized athermalized infrared objective lens of the present utility model at-40 ℃, wherein fig. 5 is a graph of optical transfer function (MTF), the horizontal axis is logarithmic per millimeter (lp/mm), the vertical axis is contrast value, fig. 6 is a dot column graph, and fig. 7 is a graph of field curvature and distortion. From the graph curves of fig. 5 to 7, it can be seen that the MTF, the root mean square value of the diffuse speck, and the field curvature and distortion at the temperature of-40 ℃ are all within the standard range.
Fig. 8 to 10 are image optical simulation data graphs of the small-sized athermalized infrared objective lens of the present utility model at 60 ℃, wherein fig. 8 is an optical transfer function (MTF) graph, the horizontal axis is logarithmic per millimeter line (lp/mm), the vertical axis is contrast value, fig. 9 is a dot column graph, and fig. 10 is a field curvature and distortion graph. From the graph curves of fig. 8 to 10, it can be seen that the MTF, the root mean square value of the diffuse speck, and the curvature of field and distortion at a temperature of 60 ℃ are all within the standard range.
Therefore, the small-size athermalized infrared objective lens has good imaging quality in a temperature range.
In summary, by means of the technical scheme, the optical lens formed by three lenses adopts the combination of different lenses and reasonably distributes optical power to realize excellent performances of small size, high resolution, heat difference elimination and the like, the ratio of optical length to focal length is 1.36, and the optical lens has the advantages of simple structure, short size and strong practicability.
The foregoing description of the preferred embodiments of the utility model is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the utility model.
Claims (8)
1. The small-size athermalized infrared objective lens is characterized by comprising a first lens (1), a second lens (2), a third lens (3) and detector protection glass (4) which are sequentially arranged on an axis; the first object side surface (11) of the first lens element (1) is convex, and the first image side surface (12) of the first lens element (1) is concave; the object side surface II (21) of the second lens element (2) is concave, and the image side surface II (22) of the second lens element (2) is convex; the object side surface III (31) of the third lens (3) is a concave surface, and the image side surface III (32) of the third lens (3) is a convex surface.
2. The small-sized athermalized infrared objective according to claim 1, wherein the first lens (1) is a negative meniscus lens, the diopter of the first lens (1) being negative.
3. The small-sized athermalized infrared objective according to claim 1, wherein the second lens (2) is a positive meniscus lens, the refractive power of the second lens (2) being positive.
4. A small-sized athermalized infrared objective according to claim 3, characterized in that the object side two (21) of the second lens (2) is provided with a diaphragm (6).
5. The small-sized athermalized infrared objective according to claim 1, wherein the third lens (3) is a meniscus positive lens.
6. The small-sized athermalized infrared objective according to claim 1, wherein the first lens (1), the second lens (2) and the third lens (3) are each provided with an aspherical surface, and the second image side surface (22) of the second lens (2) adopts an aspherical superimposed diffraction surface.
7. The small-sized athermalized infrared objective according to any one of claims 1-6, wherein the first and second lenses satisfy the following expression:
1＜f 1，2 /f＜3
wherein f 1，2 Is the combined focal length of the first lens (1) and the second lens (2), and f represents the focal length of the whole lens group.
8. The small-sized athermalized infrared objective according to any of claims 1-6, wherein the first lens (1), the second lens (2), the third lens (3) are all fixed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321505294.4U CN219997399U (en) | 2023-06-14 | 2023-06-14 | Small-size athermalization infrared objective lens |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202321505294.4U CN219997399U (en) | 2023-06-14 | 2023-06-14 | Small-size athermalization infrared objective lens |
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| Publication Number | Publication Date |
|---|---|
| CN219997399U true CN219997399U (en) | 2023-11-10 |
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|---|---|---|---|
| CN202321505294.4U Active CN219997399U (en) | 2023-06-14 | 2023-06-14 | Small-size athermalization infrared objective lens |
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- 2023-06-14 CN CN202321505294.4U patent/CN219997399U/en active Active
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