CN117192745A - Wide-spectrum athermalized refrigeration lens applicable to 1.5-5um double-color detection system - Google Patents
Wide-spectrum athermalized refrigeration lens applicable to 1.5-5um double-color detection system Download PDFInfo
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- CN117192745A CN117192745A CN202311031532.7A CN202311031532A CN117192745A CN 117192745 A CN117192745 A CN 117192745A CN 202311031532 A CN202311031532 A CN 202311031532A CN 117192745 A CN117192745 A CN 117192745A
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- 238000001514 detection method Methods 0.000 title claims abstract description 25
- 238000005057 refrigeration Methods 0.000 title claims abstract description 20
- 238000001228 spectrum Methods 0.000 title claims description 5
- 238000003384 imaging method Methods 0.000 claims description 12
- 239000013078 crystal Substances 0.000 claims description 8
- 239000005387 chalcogenide glass Substances 0.000 claims description 7
- PFNQVRZLDWYSCW-UHFFFAOYSA-N (fluoren-9-ylideneamino) n-naphthalen-1-ylcarbamate Chemical compound C12=CC=CC=C2C2=CC=CC=C2C1=NOC(=O)NC1=CC=CC2=CC=CC=C12 PFNQVRZLDWYSCW-UHFFFAOYSA-N 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 4
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 claims description 3
- 229910001634 calcium fluoride Inorganic materials 0.000 claims description 3
- 238000012544 monitoring process Methods 0.000 abstract description 8
- 238000003915 air pollution Methods 0.000 abstract description 4
- 230000003287 optical effect Effects 0.000 description 18
- 230000004075 alteration Effects 0.000 description 10
- 238000012546 transfer Methods 0.000 description 5
- 238000002834 transmittance Methods 0.000 description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 238000003331 infrared imaging Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
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Abstract
The application discloses a broad spectrum athermalized refrigeration lens applicable to a 1.5-5um bicolor detection system, which comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object space to an image space; wherein the first lens is a concave-convex lens with negative refractive index; a convex lens of positive refractive power of the second lens; the third lens is a convex-concave lens with positive refractive index; the fourth lens is a convex-concave lens with positive refractive index; the first image side surface is an aspheric surface; the third object side surface is a diffraction surface; the first object side surface, the second image side surface, the third image side surface, the fourth object side surface and the fourth image side surface are spherical lenses. The lens is suitable for short-wave and medium-wave double-color detectors, has a diagonal field angle of 27.6 degrees, is suitable for the related fields of safety monitoring, air pollution, target characteristic detection, high-speed target detection and tracking, mechanical equipment state monitoring and the like, and has high reliability.
Description
Technical Field
The application relates to a broad spectrum athermalization refrigeration lens applicable to a 1.5-5um double-color detection system, and belongs to the technical field of broad spectrum athermalization refrigeration lenses.
Background
The 1.5 um-5.0 um high-frame frequency refrigerating medium-wave infrared machine core is applied to scientific and industrial fields such as safety monitoring, air pollution, target characteristic detection, high-speed target detection tracking, mechanical equipment state monitoring and the like, and has the characteristics of high sensitivity, wide temperature measuring range, high temperature measuring precision, high measuring speed and the like.
The broadband optical system has design difficulties such as difficulty in correcting system aberration and chromatic aberration. The conventional refrigeration medium wave lens is generally and nominally applicable to 3.0-5.0 um, and practically most of the lens eliminates chromatic aberration according to the wave band of 3.7-4.8 um, and the lens can cause energy loss and 1.5-3.0 um wave band information loss when used on a machine core of 1.5-5.0 um. CN106019534B discloses a 1.3-5 um broadband infrared imaging lens, which has the problems of large lens number, large volume, small image surface, non-athermalization, inconvenient integral tooling adjustment and the like.
Disclosure of Invention
The application provides a large-breadth wide-spectrum lens suitable for a 640x512 infrared core of a short-wave and medium-wave double-color detector, which is suitable for the related fields of safety monitoring, air pollution, target characteristic detection, high-speed target detection tracking, mechanical equipment state monitoring and the like.
In order to solve the technical problems, the technical scheme adopted by the application is as follows:
a broad spectrum athermalized refrigeration lens suitable for a 1.5-5um bicolor detection system comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object space to an image space; wherein the first lens is a concave-convex lens with negative refractive index; a convex lens of positive refractive power of the second lens; the third lens is a convex-concave lens with positive refractive index; the fourth lens is a convex-concave lens with positive refractive index; from the object space to the image space, two surfaces of the first lens are a first object side surface and a first image side surface in sequence, two surfaces of the second lens are a second object side surface and a second image side surface in sequence, two surfaces of the third lens are a third object side surface and a third image side surface in sequence, and two surfaces of the fourth lens are a fourth object side surface and a fourth image side surface in sequence; the first image side surface is an aspheric surface; the third object side surface is a diffraction surface; the first object side surface, the second image side surface, the third image side surface, the fourth object side surface and the fourth image side surface are spherical lenses.
The lens is a high-frequency refrigeration lens suitable for a 640x 512-15um movement of a short-wave and medium-wave double-color detector. The application provides a solution suitable for athermalization lenses of short-wave to medium-wave double-color detectors, and fills the blank of domestic short-wave to medium-wave band athermalization imaging objective lenses.
The lens adopts a diffraction surface to carry out chromatic aberration and thermal difference optimization.
The wide-spectrum athermalized refrigeration lens applicable to the 1.5-5um double-color detection system has the combined focal length F' of 25mm, the F number of the system equal to 2.5, the diagonal imaging surface of 12.3mm and the diagonal field angle of 27.6 degrees.
The first lens to the fourth lens are made of crystal materials and chalcogenide glass. Preferably, in order to ensure the overall transmittance, reduce the number of lenses and eliminate the adverse effect of temperature change on image quality, the lenses are made of crystal materials with higher refractive index and chalcogenide glass with smaller refractive index along with temperature change coefficient dn/dT; further preferably, the first lens and the fourth lens are made of zinc selenide, and an aspheric surface is used for correcting image quality; the second lens is made of calcium fluoride crystal, the fluoride crystal has higher transmittance at 1.5-5um, and the transmittance can reach 90% under the condition of no film plating; the third lens is made of chalcogenide glass, preferably IRG206 made of home-made chalcogenide glass, and a diffraction surface is used to help eliminate chromatic aberration and thermal difference of an optical system.
To further ensure imaging, the radius of curvature of the first object side is-16.280 + -0.005 mm, and the radius of curvature of the first image side is-24.868 + -0.005 mm; the curvature radius of the second object side surface is 63.376 plus or minus 0.005mm, and the curvature radius of the second image side surface is-65.842 plus or minus 0.005mm; the radius of curvature of the third object side surface is 118.371 plus or minus 0.005mm, and the radius of curvature of the third image side surface is 159.804 plus or minus 0.005mm; the radius of curvature of the fourth object-side surface is 43.214 + -0.005 mm, and the radius of curvature of the fourth image-side surface is 110.284 + -0.005 mm.
To further secure imaging quality, the center interval between the first lens and the second lens is 11.073 ±0.005mm, the center interval between the second lens and the third lens is 0.300±0.005mm, and the center interval between the third lens and the fourth lens is 0.626±0.005mm.
To further secure imaging stability and imaging quality, the center thickness of the first lens is 7.000±0.05mm, the center thickness of the second lens is 6.200 ±0.05mm, the center thickness of the third lens is 2.700 ±0.05mm, and the center thickness of the fourth lens is 2.700 ±0.05mm.
In order to achieve both imaging quality and lens volume, the outer diameter of the first lens is 21.2-28.3 mm, the outer diameter of the second lens is 27.5+/-0.1 mm, the outer diameter of the third lens is 23.5-26.1 mm, and the outer diameter of the fourth lens is 21.8-24.7 mm.
The lens achieves 100% cold stop efficiency.
The technology not mentioned in the present application refers to the prior art.
The broad spectrum athermalized refrigeration lens applicable to the 1.5-5um double-color detection system has the following beneficial effects:
1. the method is suitable for short-wave and medium-wave double-color detectors, has a diagonal view angle of 27.6 degrees, is suitable for the related fields of safety monitoring, air pollution, target characteristic detection, high-speed target detection tracking, mechanical equipment state monitoring and the like, and has high reliability;
2. the imaging breadth is large, the imaging mechanism can be used for 640 cores, and the pixel can reach 15um;
3. the F number of the system is 2.5, the caliber of the whole optical lens is small, and the cost can be saved to the greatest extent;
4. the third object side surface adopts a diffraction surface, so that chromatic aberration and thermal difference generated by a broadband can be effectively corrected;
5. the optical system is composed of four mirrors, all elements are arranged on the same optical axis, and the optical system has the characteristics of wide working band, compact structure, good fitting property, good imaging quality, transfer function reaching or approaching diffraction limit and the like.
Drawings
FIG. 1 is a schematic view of the optical path of a broad spectrum athermalized refrigeration lens of a dual color detection system of the present application;
FIG. 2 is a graph of optical transfer function at room temperature of 20℃for a specific example at 1.5-5 um;
FIG. 3 is a graph of optical transfer function at low temperature of 1.5-5um to 40℃for the example;
FIG. 4 is a graph of the optical transfer function of a particular embodiment at a high temperature of 80℃of 1.5-5 um;
FIG. 5 is a graph of field curvature and distortion at 1.5-5um for an embodiment;
FIG. 6 is a spot diagram of an embodiment at 1.5-5 um;
FIG. 7 is a graph of vertical axis color difference between 1.5 and 5um for a specific example.
Detailed Description
For a better understanding of the present application, the following examples are further illustrated, but are not limited to the following examples.
The broad spectrum athermalized refrigeration lens suitable for the 1.5-5um bicolor detection system as shown in fig. 1 comprises the following components sequentially arranged from an object side to an image side along an optical axis: a first lens L1 with negative focal power, a second lens L2 with positive focal power, a third lens L3 with positive focal power, a fourth lens L4 with positive focal power, a protective window L5, a system cold stop S11 and an imaging surface S12.
From the object side to the image side, the two surfaces of the first lens L1 are a first object side surface S1 and a first image side surface S2 in sequence, the two surfaces of the second lens L2 are a second object side surface S3 and a second image side surface S4 in sequence, the two surfaces of the third lens L3 are a third object side surface S5 and a third image side surface S6 in sequence, the two surfaces of the fourth lens L4 are a fourth object side surface S7 and a fourth image side surface S8 in sequence, and the two surfaces of the protection window L6 are a sixth object side surface S9 and a sixth image side surface S10; the first image side surface S2 is an aspheric surface; the third object side surface S5 is a diffraction surface; the first object side surface S1, the second object side surface S3, the second image side surface S4, the third image side surface S6, the fourth object side surface S7 and the fourth image side surface S8 are spherical lenses.
The first lens L1 is made of zinc selenide, and uses an aspheric surface to correct image quality;
the second lens L2 adopts calcium fluoride crystal, the fluoride crystal has higher transmittance at 1.5-5um, and the transmittance can reach 90% under the condition of no film plating;
the third lens L3 uses the chalcogenide glass IRG206, uses a diffraction surface, and contributes to eliminating chromatic aberration and thermal difference of an optical system;
the fourth lens L4 is made of zinc selenide and integrates the aberration function.
Table 1 technical parameters of the optical system according to the embodiment of the application
| Focal length | 25mm |
| Wave band | 1.5-5um |
| F# | 2.5 |
| Visual field | (H)21.7°*(V)17.5°*(D)27.6° |
| Distortion of | ≤|4％| |
| Detector specification | 640*512-15um |
| Cold diaphragm size | 8.37mm |
TABLE 2 specific parameters of the examples of the application
The aspherical equation employed in table 2:
wherein the meaning of the amounts is as follows:
ZA: the aspherical surface is higher than the lens vector in the optical axis direction;
r: radius of curvature at the intersection of the surface and the optical axis;
y: the half caliber of the lens is vertical to the optical axis direction;
k: a conic coefficient;
A. b, C, D area coefficient; the specific coefficients are shown in Table 3.
TABLE 3 Table 3
| Aspherical surface | K | A | B | C | D |
| S2 | 0 | -4.58781E-06 | -5.99653E-010 | -6.88452E-011 | 1.06469E-013 |
| S5 | 0 | -1.91318E-06 | 1.61548E-09 | -5.39029E-011 | 1.79397E-013 |
The diffraction plane equation used in table 2 is:
Φ＝A 1 Y 2 +A 2 Y 4 +A 3 Y 6
wherein:
Φ: is the phase of the diffraction plane;
y: the half caliber of the lens is vertical to the optical axis direction;
a1, A2 and A3 diffraction surface phase coefficients;
table 2 the diffraction plane coefficients used in the specific examples are shown in table 4.
TABLE 4 Table 4
| Diffraction plane | Diffraction orders | Center wavelength of | A1 | A2 | A3 |
| S5 | +1 | 3um | -7.2844E-04 | -3.1355E-07 | 0 |
FIGS. 2-4 are graphs of optical transfer functions for the examples at temperatures of-40 ℃, +20 ℃ and +80 ℃ for 33 line pair/mm resolution with a 640x51215 μm detector; as can be seen from fig. 2 to fig. 4, the edge MTF values are all above 0.28 along with the temperature change, and the resolution capability and athermalization effect of the image are good; as can be seen from FIG. 6, the diffuse spots of the system are smaller, and the recognition capability of the system to objects is stronger; as can be seen from fig. 7, the vertical axis chromatic aberration is basically controlled within the diffraction limit airy disk, and the chromatic aberration correction is good.
Claims (8)
1. A wide spectrum athermalization refrigeration lens suitable for a 1.5-5um double-color detection system is characterized in that: the lens comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object side to an image side; wherein the first lens is a concave-convex lens with negative refractive index; a convex lens of positive refractive power of the second lens; the third lens is a convex-concave lens with positive refractive index; the fourth lens is a convex-concave lens with positive refractive index; from the object space to the image space, two surfaces of the first lens are a first object side surface and a first image side surface in sequence, two surfaces of the second lens are a second object side surface and a second image side surface in sequence, two surfaces of the third lens are a third object side surface and a third image side surface in sequence, and two surfaces of the fourth lens are a fourth object side surface and a fourth image side surface in sequence; the first image side surface is an aspheric surface; the third object side surface is a diffraction surface; the first object side surface, the second image side surface, the third image side surface, the fourth object side surface and the fourth image side surface are spherical lenses.
2. The broad spectrum athermalized refrigeration lens suitable for a 1.5-5um dual-color detection system as claimed in claim 1, wherein: the combined focal length F' of the system is 25mm, the F number of the system is equal to 2.5, the imaging surface of the diagonal line is 12.3mm, and the angle of view of the diagonal line reaches 27.6 degrees.
3. The broad spectrum athermalized refrigeration lens applicable to a 1.5-5um dual-color detection system as claimed in claim 1 or 2, wherein: the materials used for the first lens to the fourth lens are crystal materials or chalcogenide glass.
4. The broad spectrum athermalized refrigeration lens suitable for a 1.5-5um dual-color detection system as claimed in claim 3, wherein the first lens is made of zinc selenide; the second lens is made of calcium fluoride crystal; the third lens is made of chalcogenide glass; the fourth lens is made of zinc selenide.
5. The broad spectrum athermalized refrigeration lens applicable to a 1.5-5um dual-color detection system as claimed in claim 1 or 2, wherein: the curvature radius of the first object side surface is-16.280 plus or minus 0.005mm, and the curvature radius of the first image side surface is-24.868 plus or minus 0.005mm; the curvature radius of the second object side surface is 63.376 plus or minus 0.005mm, and the curvature radius of the second image side surface is-65.842 plus or minus 0.005mm; the radius of curvature of the third object side surface is 118.371 plus or minus 0.005mm, and the radius of curvature of the third image side surface is 159.804 plus or minus 0.005mm; the radius of curvature of the fourth object-side surface is 43.214 + -0.005 mm, and the radius of curvature of the fourth image-side surface is 110.284 + -0.005 mm.
6. The broad spectrum athermalized refrigeration lens applicable to a 1.5-5um dual-color detection system as claimed in claim 1 or 2, wherein: the center interval between the first lens and the second lens is 11.073 + -0.005 mm, the center interval between the second lens and the third lens is 0.300+ -0.005 mm, and the center interval between the third lens and the fourth lens is 0.626+ -0.005 mm.
7. The broad spectrum athermalized refrigeration lens applicable to a 1.5-5um dual-color detection system as claimed in claim 1 or 2, wherein: the center thickness of the first lens is 7.000 + -0.05 mm, the center thickness of the second lens is 6.200 + -0.05 mm, the center thickness of the third lens is 2.700 + -0.05 mm, and the center thickness of the fourth lens is 2.700 + -0.05 mm.
8. The broad spectrum athermalized refrigeration lens applicable to a 1.5-5um dual-color detection system as claimed in claim 1 or 2, wherein: the outer diameter of the first lens is 21.2-28.3 mm, the outer diameter of the second lens is 27.5+/-0.1 mm, the outer diameter of the third lens is 23.5-26.1 mm, and the outer diameter of the fourth lens is 21.8-24.7 mm.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311031532.7A CN117192745A (en) | 2023-08-16 | 2023-08-16 | Wide-spectrum athermalized refrigeration lens applicable to 1.5-5um double-color detection system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311031532.7A CN117192745A (en) | 2023-08-16 | 2023-08-16 | Wide-spectrum athermalized refrigeration lens applicable to 1.5-5um double-color detection system |
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| CN117192745A true CN117192745A (en) | 2023-12-08 |
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