Super-large aperture long-wave infrared double-view-field optical system
By designing a long-wave infrared dual-field optical system with a lens combination of meniscus lens and a single convex lens, the problems of low transmittance and high cost of the long-wave infrared system are solved, efficient target recognition and large-field search are achieved, and the number of lenses and processing difficulty is reduced.
Patent Information
- Application Number
- CN202422343284.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-25
- Publication Date
- 2025-07-08
- Estimated Expiration
- 2034-09-25
AI Technical Summary
In the existing long-wave infrared systems, the use of diffraction surfaces leads to low transmittance and high cost, especially in large aperture designs, which increases the processing difficulty and cost.
The ultra-large aperture long-wave infrared dual-field optical system is adopted, including the front fixing group, the field-cutting mirror group and the rear fixing group. The lens is designed as a meniscus lens and a single convex lens. Large and small field-of-view switching is achieved through the inlet and out of the field-cutting mirror group, reducing the number of lenses. Single crystal germanium and multi-spectral zinc sulfide materials are used to design the imaging target surface and large aperture, and are suitable for non-refrigeration detectors.
It improves the transmittance of the optical system and reduces costs, enhances the recognition ability of low, small and slow targets, improves the space utilization and optical axis stability, and short field of view switching time.
Smart Images
Figure CN223078558U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of long-wave infrared, and particularly relates to a super-large aperture long-wave infrared dual-field optical system. Background Art
[0002] Infrared imaging optical systems have good environmental adaptability, strong concealment, and the ability of day and night monitoring, and are applicable to fields such as military, medical, security, and remote sensing. With the development of uncooled long-wave infrared detectors, their array scale, pixel size, and noise equivalent temperature difference have all been improved, and uncooled detectors do not require refrigeration, have small volume, low power consumption, low cost, long life, and are convenient to use.
[0003] Due to the target radiation characteristics of long-wave infrared, when imaging point targets in the air, the target radiation intensity of long-wave infrared is better than that of mid-wave infrared systems. For optoelectronic systems used for target search and recognition, it is required that the infrared thermal imaging system can both achieve large-field target search and small-field recognition of long-distance targets.
[0004] However, because infrared materials are expensive, the processing cost is high, and the diffraction limit of long-wave infrared is low, in order to make long-wave infrared have higher energy, a large aperture design is generally required and the number of infrared lenses is reduced to increase energy. Most domestic designs of large aperture dual-field long-wave infrared currently use diffractive surfaces to correct chromatic aberration. The use of diffractive surfaces will reduce the energy transmittance of the lens, and increase the lens processing difficulty and cost. Summary of the Utility Model
[0005] In view of the above analysis, the utility model aims to provide a super-large aperture long-wave infrared dual-field optical system to solve the problems of low transmittance and high cost caused by the use of diffractive surfaces and a large number of lenses in existing long-wave infrared systems.
[0006] The purpose of the utility model is mainly achieved through the following technical solutions:
[0007] The utility model provides a super-large aperture long-wave infrared dual-field optical system, which includes a front fixed group with positive optical power, a field cutting lens group with positive optical power, a rear fixed group with positive optical power, and a filter with zero optical power, which are sequentially arranged along the optical axis from the object side to the image side; wherein, the switching between large and small fields is realized by the cutting-in and cutting-out of the field cutting lens group; wherein,
[0008] The front fixed group includes a front fixed lens arranged along the optical axis; wherein, the front fixed lens is a meniscus lens;
[0009] The field cutting lens group includes a first field cutting lens and a second field cutting lens arranged along the optical axis from the object side to the image side; wherein, the first field cutting lens is a meniscus lens, and the second field cutting lens is a plano-convex lens;
[0010] The rear fixed group includes a first rear fixed lens and a second rear fixed lens arranged along the optical axis in sequence from the object side to the image side; wherein, both the first rear fixed lens and the second rear fixed lens are meniscus lenses.
[0011] Based on a further improvement of the above solution, the front fixed lens has a positive optical power, and its convex surface faces the object side.
[0012] Based on a further improvement of the above solution, the first field cutting lens has a negative optical power, and its concave surface faces the object side; the second field cutting lens has a positive optical power, and its convex surface faces the object side.
[0013] Based on a further improvement of the above solution, the first rear fixed lens has a positive optical power, and its convex surface faces the object side; the second rear fixed lens has a positive optical power, and its convex surface faces the object side.
[0014] Based on a further improvement of the above solution, the material of the filter is germanium.
[0015] Based on a further improvement of the above solution, the materials of the front fixed lens, the first field cutting lens, the second field cutting lens, and the second rear fixed lens are all single crystal germanium, and the material of the first rear fixed lens is multi-spectral zinc sulfide.
[0016] Based on a further improvement of the above solution, each lens in the optical system is a single-sided aspherical surface; wherein, the convex surface of the front fixed lens facing the object side, the concave surface of the first field cutting lens facing the object side, the convex surface of the second field cutting lens facing the object side, the convex surface of the first rear fixed lens facing the object side, and the concave surface of the second rear fixed lens facing the image side are aspherical surfaces.
[0017] Based on a further improvement of the above solution, when the field cutting lens group cuts out, the optical system is a small field of view; when the field cutting lens group cuts in, the optical system is a large field of view; wherein, the focal lengths of the large field of view and the small field of view are 25mm and 100mm respectively, and the zoom ratio of the large field of view and the small field of view is 4.
[0018] Based on a further improvement of the above solution, the aperture of the optical system is 0.9, and the scale of the focal plane array can reach 1024*768@12um.
[0019] Based on a further improvement of the above solution, the working wavelength of the optical system is 8-12um, and the system distortion is less than 3%.
[0020] Compared with the prior art, the present utility model can at least achieve one of the following beneficial effects:
[0021] An ultra-large aperture long-wave infrared dual-field optical system provided by the present utility model includes a front fixed group with positive optical power, a field cutting lens group with positive optical power, a rear fixed group with positive optical power, and a filter with zero optical power, which are sequentially arranged along the optical axis from the object side to the image side. The front fixed group includes a front fixed lens arranged along the optical axis, and the front fixed lens is a meniscus lens. The field cutting lens group includes a first field cutting lens and a second field cutting lens arranged along the optical axis from the object side to the image side. The first field cutting lens is a meniscus lens and the second field cutting lens is a single convex lens. The rear fixed group includes a first rear fixed lens and a second rear fixed lens arranged along the optical axis from the object side to the image side, and both the first rear fixed lens and the second rear fixed lens are meniscus lenses. The optical system thus formed solves the problems of low transmittance and high cost caused by the use of diffractive surfaces and a large number of lenses in long-wave infrared systems, is adapted to long-wave infrared uncooled detectors, has a low cost, and long-wave infrared can be applied to the search and identification of airborne point targets due to its target radiation characteristics, especially having great advantages for low, small, and slow targets. Moreover, the designed optical system has a large imaging target surface and a large aperture, which can improve the detectable range of the optical system and increase the probability of target identification. In addition, the conversion between the large field of view and the small field of view is realized by the cutting in and out of the field cutting group, effectively increasing the space utilization rate. The in-place accuracy of the field cutting position is high, which is beneficial to increasing the stability of the optical axis, and the field of view switching time is short.
[0022] In the present utility model, the above technical solutions can also be combined with each other to achieve more preferred combined solutions. Other features and advantages of the present utility model will be described in the following content. Moreover, some advantages can be made obvious from the description or understood by implementing the present utility model. The objectives and other advantages of the present utility model can be realized and obtained from the content specifically pointed out in the text and the drawings. Description of the Drawings
[0023] The drawings are only for the purpose of showing specific embodiments and are not considered as limitations to the present utility model. Throughout the drawings, the same reference signs represent the same components.
[0024] Figure 1 It is a schematic structural diagram of the large field of view optical system in the ultra-large aperture long-wave infrared dual-field optical system provided by the present utility model;
[0025] Figure 2 It is a schematic structural diagram of the ultra-large aperture long-wave infrared small field of view optical system with the field cutting lens group cut out provided by the present utility model;
[0026] Figure 3 It is an optical modulation transfer function diagram in the large field of view and short focal length working state provided by the present utility model;
[0027] Figure 4 It is an optical modulation transfer function diagram in the small field of view and long focal length working state provided by the present utility model;
[0028] Reference Signs:
[0029] 11 - Front fixed lens; 21 - First field - cutting lens; 22 - Second field - cutting lens; 31 - First rear fixed lens; 32 - Second rear fixed lens; 41 - Filter. Detailed Embodiment
[0030] The following combines the accompanying drawings to specifically describe the preferred embodiments of the present invention. Among them, the accompanying drawings form a part of this application and are used together with the embodiments of the present invention to explain the principle of the present invention, and are not used to limit the scope of the present invention.
[0031] A specific embodiment of the present invention discloses a large - aperture long - wave infrared dual - field - of - view optical system. As Figure 1 shown, it includes a front fixed group with positive optical power, a field - cutting lens group with positive optical power, a rear fixed group with positive optical power, and a filter 41 with zero optical power, which are sequentially arranged along the optical axis from the object side to the image side; among them, the switching between the large and small fields of view is realized by the cutting - in and cutting - out of the field - cutting lens group; among them,
[0032] The front fixed group includes a front fixed lens 11 arranged along the optical axis; among them, the front fixed lens 11 is a meniscus lens;
[0033] The field - cutting lens group includes a first field - cutting lens 21 and a second field - cutting lens 22 arranged sequentially along the optical axis from the object side to the image side; among them, the first field - cutting lens 21 is a meniscus lens, and the second field - cutting lens 22 is a single - convex lens;
[0034] The rear fixed group includes a first rear fixed lens 31 and a second rear fixed lens 32 arranged sequentially along the optical axis from the object side to the image side; among them, both the first rear fixed lens 31 and the second rear fixed lens 32 are meniscus lenses.
[0035] During implementation, the front fixed lens 11 has positive optical power, and its convex surface faces the object side.
[0036] During implementation, the first field - cutting lens 21 has negative optical power, and its concave surface faces the object side; the second field - cutting lens 22 has positive optical power, and its convex surface faces the object side.
[0037] During implementation, the first rear fixed lens 31 has positive optical power, and its convex surface faces the object side; the second rear fixed lens 32 has positive optical power, and its convex surface faces the object side.
[0038] Specifically, the material of the filter 41 is germanium.
[0039] Specifically, the materials of the front fixed lens 11, the first field cutting lens 21, the second field cutting lens 22, and the second rear fixed lens 32 are all single crystal germanium, and the material of the first rear fixed lens 31 is multi-spectral zinc sulfide.
[0040] Specifically, each lens in the optical system is a single-sided aspherical lens; among them, the convex surface of the front fixed lens 11 facing the object side, the concave surface of the first field cutting lens 21 facing the object side, the convex surface of the second field cutting lens 22 facing the object side, the convex surface of the first rear fixed lens 31 facing the object side, and the concave surface of the second rear fixed lens 32 facing the image side are aspherical surfaces.
[0041] Specifically, when the field cutting lens group cuts out, the optical system has a small field of view; when the field cutting lens group cuts in, the optical system has a large field of view; among them, the focal lengths of the large field of view and the small field of view are 25 mm and 100 mm respectively, and the zoom ratio of the large field of view and the small field of view is 4.
[0042] Specifically, when the field cutting lens group cuts out, the small field of view of the optical system consists of the front fixed group and the rear fixed group, which is beneficial to ensuring the optical axis stability of the small field of view. The number of lenses is only 3, which is beneficial to improving the transmittance, and further improving the probability of target recognition in the small field of view; when the field cutting lens cuts in, the large field of view of the optical system consists of the front fixed group, the field cutting group and the rear fixed group.
[0043] It can be understood that the large field of view of the optical system is used for target detection to achieve large-range search, and the small field of view is used for target recognition; and the large and small fields of view in this optical system adopt a variable aperture design. The aperture of the small field of view is the front fixed lens 11, and the aperture of the large field of view is the single convex lens of the field cutting lens group. Through the cooperation of the two apertures, a double-field large-aperture design can be achieved, and the size of the long-wave infrared optical lens can be reduced to a certain extent, which is beneficial to the miniaturization of the design.
[0044] Specifically, the aperture of the optical system is 0.9, and the focal plane array scale can reach 1024*768@12um. That is to say, the sensor array has 1024 columns and 768 rows of pixels, and the physical size of a single pixel is 12 microns.
[0045] Preferably, the optical system can also be downward compatible. The aperture can also be 1, and the array scale of the focal plane can be 640*512@15um or 320*256@25um. That is to say, the sensor array has 640 columns and 512 rows of pixels and the physical size of a single pixel is 15 microns, or the sensor array has 320 columns and 256 rows of pixels and the physical size of a single pixel is 25 microns.
[0046] Specifically, the working wavelength of the optical system is 8-12um, and the system distortion is less than 3%.
[0047] More specifically, the parameters of each lens of the optical system in this embodiment are shown in Table 1.
[0048] Table 1 Parameters of Each Lens of the Optical System
[0049]
[0050] More specifically, the aspheric formula is as follows:
[0051]
[0052] In the formula, Z is the position in the optical axis direction, r is the radial height, c is the radius of curvature, k is the conic coefficient, and A, B, C, and D are aspheric coefficients. As shown in Table 2, it is the aspheric coefficient table.
[0053] Table 2 Aspheric Coefficient Table
[0054] Surface k A B C D S1 0 -6.057E-09 -9.036E-013 0 0 S3 0 8.545E-07 3.953E-010 -1.512E-013 0 S6 0 4.723E-07 -5.525E-011 0 0 S7 0 1.397E-07 2.751E-010 -7.031E-014 0 S10 0 -7.391E-08 1.4486E-09 -1.141E-012 0
[0055] As Figure 3 shown, it is the optical modulation transfer function diagram in the large field of view and short focal length working state. As Figure 4 shown, it is the optical modulation transfer function diagram in the small field of view and long focal length working state. Both are the core indicators for evaluating the imaging quality of the lens; when the characteristic frequency on the abscissa is 42 lp / mm, the diffraction limit on the ordinate is 0.48. After selecting a reasonable material combination and configuration, except for the edge field of view, the MTF (optical modulation transfer function) of the system is close to the diffraction limit, and the imaging quality is good.
[0056] Compared with the prior art, the present embodiment provides a long-wave infrared dual-field-of-view optical system with a super-large aperture, including a front fixed group with a positive focal power, a field-splitting lens group with a positive focal power, a rear fixed group with a positive focal power, and a filter with no focal power, which are sequentially arranged along the optical axis from the object side to the image side. The front fixed group includes a front fixed lens arranged along the optical axis, and the front fixed lens is a meniscus lens. The field-splitting lens group includes a first field-splitting lens and a second field-splitting lens arranged sequentially along the optical axis from the object side to the image side. The first field-splitting lens is a meniscus lens and the second field-splitting lens is a plano-convex lens. The rear fixed group includes a first rear fixed lens and a second rear fixed lens arranged sequentially along the optical axis from the object side to the image side, and both the first rear fixed lens and the second rear fixed lens are meniscus lenses. The optical system thus formed solves the problems of low transmittance and high cost caused by the use of diffractive surfaces and a large number of lenses in the long-wave infrared system, and is adapted to long-wave infrared uncooled detectors, with low cost. Due to its target radiation characteristics, long-wave infrared can be applied to the search and identification of airborne point targets, especially having great advantages for low, small, and slow targets. Moreover, the designed optical system has a large imaging target surface and a large aperture, which can improve the detectable range of the optical system and the probability of target recognition. In addition, the conversion between the large field of view and the small field of view is realized by the insertion and extraction of the field-splitting group, effectively increasing the space utilization rate. The field-splitting position has high in-place accuracy, which is beneficial to increasing the optical axis stability, and the field-of-view switching time is short.
[0057] As mentioned above, the above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.
Claims
1. An ultra-large aperture long-wave infrared dual-field-of-view optical system, characterized in that, It includes a front fixed group with positive optical power, a field cutting lens group with positive optical power, a rear fixed group with positive optical power, and a filter with zero optical power, which are arranged along the optical axis in sequence from the object side to the image side; wherein, the switching between large and small fields of view is achieved by the cutting in and out of the field cutting lens group; wherein, The front fixed group includes a front fixed lens arranged along the optical axis; wherein, the front fixed lens is a meniscus lens; The field cutting lens group includes a first field cutting lens and a second field cutting lens arranged along the optical axis in sequence from the object side to the image side; wherein, the first field cutting lens is a meniscus lens, and the second field cutting lens is a single convex lens; The rear fixed group includes a first rear fixed lens and a second rear fixed lens arranged along the optical axis in sequence from the object side to the image side; wherein, both the first rear fixed lens and the second rear fixed lens are meniscus lenses.
2. The ultra-large aperture long-wave infrared dual-field-of-view optical system according to claim 1, characterized in that, The front fixed lens has positive optical power, and its convex surface faces the object side.
3. The ultra-large aperture long-wave infrared dual-field optical system according to claim 1, wherein, The first field cutting lens has negative optical power, and its concave surface faces the object side; the second field cutting lens has positive optical power, and its convex surface faces the object side.
4. The super-large aperture long-wave infrared dual-field-of-view optical system according to claim 1, characterized in that, The first rear fixed lens has positive optical power, and its convex surface faces the object side; the second rear fixed lens has positive optical power, and its convex surface faces the object side.
5. The ultra-large aperture long-wave infrared dual-field-of-view optical system according to any one of claims 1-4, characterized in that The material of the filter is germanium.
6. The ultra-large aperture long-wave infrared dual-field-of-view optical system according to claim 1, characterized in that The materials of the front fixed lens, the first field cutting lens, the second field cutting lens, and the second rear fixed lens are all single crystal germanium, and the material of the first rear fixed lens is multi-spectral zinc sulfide.
7. The ultra-large aperture long-wave infrared dual-field-of-view optical system according to claim 1, wherein, Each lens in the optical system is a single-sided aspherical surface; wherein, the convex surface of the front fixed lens facing the object side, the concave surface of the first field cutting lens facing the object side, the convex surface of the second field cutting lens facing the object side, the convex surface of the first rear fixed lens facing the object side, and the concave surface of the second rear fixed lens facing the image side are aspherical surfaces.
8. The ultra-large aperture long-wave infrared dual-field-of-view optical system according to claim 1, wherein When the field cutting lens group cuts out, the optical system is in a small field of view; when the field cutting lens group cuts in, the optical system is in a large field of view; wherein, the focal lengths of the large field of view and the small field of view are 25mm and 100mm respectively, and the zoom ratio of the large field of view and the small field of view is 4.
9. The super-large aperture long-wave infrared dual-field-of-view optical system according to claim 1, characterized in that, The aperture of the optical system is 0.9, and the scale of the focal plane array can reach 1024*768@12um.
10. The ultra-large aperture long-wave infrared dual-field-of-view optical system according to claim 1, characterized in that, The working wavelength of the optical system is 8 - 12um, and the system distortion is less than 3%.