Far infrared optical system and far infrared optical lens
The remote infrared optical system addresses the challenge of high imaging quality and cost by employing a sequence of aspherical and hyper lenses with micro-nano structures, achieving compact size and cost-effectiveness.
Patent Information
- Application Number
- CN202422438817.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-10
- Publication Date
- 2025-07-15
- Estimated Expiration
- 2034-10-10
AI Technical Summary
Existing remote infrared optical systems face challenges in achieving high imaging quality while maintaining a compact size and low cost, often requiring multiple lenses or expensive materials like germanium lenses, which increase cost and size, limiting their applications.
A remote infrared optical system comprising a sequence of lenses including a first and second aspherical lens and a hyper lens with micro-nano structures, optimized to achieve high imaging quality with reduced size and cost through efficient use of materials.
The system achieves excellent imaging quality with a compact form factor and lower cost by using fewer lenses and cost-effective hyper lenses, suitable for various applications.
Smart Images
Figure CN223108149U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical systems, and particularly to a far-infrared optical system and a far-infrared optical lens. Background Art
[0002] A far-infrared optical system is an optical system that uses far-infrared light for imaging.
[0003] With the development of technology, the market has higher requirements for the imaging quality of far-infrared optical systems. In the prior art, the imaging quality of far-infrared optical systems is usually improved by setting multiple lenses or using germanium lenses with higher costs. Although the above methods can improve the imaging quality of far-infrared optical systems, they will also significantly increase the cost and volume of far-infrared optical systems while improving the imaging quality. The large volume of far-infrared optical systems will severely limit their application scenarios. Summary of the Utility Model
[0004] In view of the above technical problems, the embodiments of this application provide a far-infrared optical system and a far-infrared optical lens, aiming to provide a far-infrared optical system with better imaging quality, lower cost, and smaller volume.
[0005] According to one aspect of the embodiments of this application, a far-infrared optical system is disclosed. The far-infrared optical system sequentially includes, from the object side to the image side along the optical axis: a first aspheric lens, a metasurface lens, and a second aspheric lens; the optical power of the first aspheric lens is positive, the object side surface of the first aspheric lens bulges towards the object side, and the image side surface of the first aspheric lens bulges towards the object side; the optical power of the metasurface lens is positive, and the metasurface lens includes: a substrate and a micro-nano structure, and the micro-nano structure is disposed on the object side surface and / or the image side surface of the substrate; the optical power of the second aspheric lens is positive;
[0006] Wherein, the far-infrared optical system satisfies: f m >f a1 >f a2 wherein, the f m is the focal length of the metasurface lens, the f a1 is the focal length of the first aspheric lens, and the f a2 is the focal length of the second aspheric lens.
[0007] In some embodiments, the far-infrared optical system satisfies: Wherein, the FOV is the maximum field of view angle of the far-infrared optical system, the TTL is the total optical length of the far-infrared optical system, and the f is the effective focal length of the far-infrared optical system.
[0008] In some embodiments, the far-infrared optical system satisfies: Wherein, L is the distance between the image side surface of the second aspherical lens and the image plane of the far-infrared optical system on the optical axis, and f is the effective focal length of the far-infrared optical system.
[0009] In some embodiments, the far-infrared optical system satisfies: Wherein, r1 is half of the effective diameter of the object side surface of the first aspherical lens, r2 is half of the effective diameter of the image side surface of the first aspherical lens, R1 is the curvature radius of the object side surface of the first aspherical lens, R2 is the curvature radius of the image side surface of the first aspherical lens, and CT1 is the central thickness of the first aspherical lens.
[0010] In some embodiments, the far-infrared optical system satisfies: Wherein, r3 is half of the effective diameter of the object side surface of the second aspherical lens, r4 is half of the effective diameter of the image side surface of the second aspherical lens, R3 is the curvature radius of the object side surface of the second aspherical lens, R4 is the curvature radius of the image side surface of the second aspherical lens, and CT2 is the central thickness of the second aspherical lens.
[0011] In some embodiments, the far-infrared optical system satisfies: Wherein, the is the maximum phase difference of the metasurface lens, r m is half of the effective diameter of the metasurface lens, and CT m is the central thickness of the metasurface lens.
[0012] In some embodiments, the far-infrared optical system satisfies: Wherein, f is the effective focal length of the far-infrared optical system, and EPD is the entrance pupil diameter of the far-infrared optical system.
[0013] In some embodiments, the far-infrared optical system satisfies: Wherein, SAG2 is the sagitta of the image side surface of the first aspherical lens at the target point, and the target point is the point where the vertical distance from the intersection of the image side surface of the first aspherical lens and the optical axis is equal to half of the effective diameter of the image side surface of the first aspherical lens; r2 is half of the effective diameter of the image side surface of the first aspherical lens.
[0014] In some embodiments, the far-infrared optical system further includes a stop, and the stop is disposed between any two adjacent lenses; or, the stop is disposed on the object side of the first aspherical lens.
[0015] In a second aspect of the embodiments of the present application, a far-infrared optical lens is provided. The far-infrared optical lens includes: an imaging detector and the far-infrared optical system as described in any one of the above; the imaging detector is disposed on the image plane of the far-infrared optical system.
[0016] The far-infrared optical system provided in the present application sequentially includes, along the optical axis from the object side to the image side: a first aspherical lens, a metasurface lens, and a second aspherical lens; the first aspherical lens has a positive optical power, the object side surface of the first aspherical lens bulges toward the object side, and the image side surface of the first aspherical lens bulges toward the object side; the metasurface lens has a positive optical power, and the metasurface lens includes: a substrate and a micro-nano structure, and the micro-nano structure is disposed on the object side surface and / or the image side surface of the substrate; the second aspherical lens has a positive optical power. Among them, the far-infrared optical system satisfies: f m > f a1 > f a2 , where f m is the focal length of the metasurface lens, f a1 is the focal length of the first aspherical lens, and f a2 is the focal length of the second aspherical lens. The far-infrared optical system provided in the present application has better imaging quality and a smaller overall optical length, so that the far-infrared optical system has a smaller volume. The number of lenses in the far-infrared optical system is small, so that the cost of the far-infrared optical system is low. Moreover, the cost of a single metasurface lens in the far-infrared optical system is low during mass production, which can further reduce the cost of the far-infrared optical system. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] By referring to the accompanying drawings and describing its exemplary embodiments in detail, the above and other objectives, features, and advantages of the present application will become more apparent.
[0018] Figure 1 FIG. shows a schematic diagram of the architecture layout of the far-infrared optical system in an embodiment of the present application.
[0019] Figure 2 FIG. shows the MTF field curve graph of the far-infrared optical system in an embodiment of the present application.
[0020] Figure 3 FIG. shows the field curvature graph of the far-infrared optical system in an embodiment of the present application.
[0021] Figure 4 FIG. shows the distortion graph of the far-infrared optical system in an embodiment of the present application.
[0022] Figure 5 FIG. shows a schematic diagram of the architecture layout of the far-infrared optical system in an embodiment of the present application.
[0023] Figure 6Shows the MTF field curve diagram of the far-infrared optical system according to an embodiment of the present application.
[0024] Figure 7 Shows the field curvature diagram of the far-infrared optical system according to an embodiment of the present application.
[0025] Figure 8 Shows the distortion diagram of the far-infrared optical system according to an embodiment of the present application.
[0026] Figure 9 Shows the schematic diagram of the architecture layout of the far-infrared optical system according to an embodiment of the present application.
[0027] Figure 10 Shows the MTF field curve diagram of the far-infrared optical system according to an embodiment of the present application.
[0028] Figure 11 Shows the field curvature diagram of the far-infrared optical system according to an embodiment of the present application.
[0029] Figure 12 Shows the distortion diagram of the far-infrared optical system according to an embodiment of the present application.
[0030] Reference numerals
[0031] 100, far-infrared optical system;
[0032] 10, first aspherical lens;
[0033] 20, metasurface lens; 210, substrate; 220, micro-nano structure;
[0034] 30, second aspherical lens;
[0035] 40, aperture;
[0036] 50, protective glass;
[0037] A, object plane; B, image plane; S, optical axis. Detailed implementation manners
[0038] Now, example embodiments will be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in various forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more complete and comprehensive, and the concept of the example embodiments will be fully conveyed to those skilled in the art. The drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and thus their repeated description will be omitted.
[0039] In addition, the described features, structures, or characteristics may be combined in any suitable manner in one or more exemplary embodiments. In the following description, numerous specific details are provided to give a thorough understanding of the exemplary embodiments of the present application. However, those skilled in the art will realize that one or more of the specific details may be omitted to practice the technical solutions of the present application, or other modules, components, etc. may be adopted. In other cases, well-known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of the present application.
[0040] Please refer to Figure 1 , Figure 1 which shows a schematic diagram of the architecture layout of the far-infrared optical system 100 in an embodiment of the present application. Herein, the optical axis S is the center line of the light beam. In Figure 1 , the object is located on the left side of the leftmost lens, that is, the object side is on the left side of the leftmost lens, and the object plane A is located on the object side. The image formed by the far-infrared optical system 100 is located on the right side of the rightmost lens, that is, the image side is on the right side of the rightmost lens, and the image plane B is located on the image side. Therefore, the direction from the object plane A to the image plane B along the optical axis S is the same as the direction from the object side to the image side along the optical axis S.
[0041] For each optical element of the far-infrared optical system 100, the side close to the object side is the object side of the corresponding optical element, and the side close to the image side is the image side of the corresponding optical element. For example, the side of the aperture 40 close to the object side is the object side of the aperture 40. For each optical element of the far-infrared optical system 100, the surface close to the object side is the object side surface of the corresponding optical element, and the surface close to the image side is the image side surface of the corresponding optical element. For example, the surface of the aperture 40 close to the image side is the image side surface of the aperture 40.
[0042] The far-infrared optical system 100 includes: a first aspherical lens 10, a meta-lens 20, and a second aspherical lens 30. Among them, the first aspherical lens 10, the meta-lens 20, and the second aspherical lens 30 are arranged in sequence along the direction from the object side to the image side of the optical axis S.
[0043] The optical power of the first aspherical lens 10 is positive. The object side surface of the first aspherical lens 10 bulges towards the object side, and the image side surface of the first aspherical lens 10 bulges towards the object side.
[0044] The optical power of the meta-lens 20 is positive. The meta-lens 20 includes: a substrate 210 and a micro-nano structure 220. The micro-nano structure 220 is arranged on the object side surface and / or the image side surface of the substrate 210. According to the adopted phase modulation method, the corresponding phase modulation formula can be adaptively used to configure the parameters of the micro-nano structure 220, so that the meta-lens 20 has the expected optical performance.
[0045] The optical power of the second aspherical lens 30 is positive.
[0046] The far-infrared optical system 100 satisfies Conditional Expression 1: f m > f a1 > f a2 , where f m is the focal length of the meta-lens 20, f a1 is the focal length of the first aspherical lens 10, and f a2 is the focal length of the second aspherical lens 30. Through Conditional Expression 1, the optical power of the far-infrared optical system 100 can be reasonably distributed, ensuring that the meta-lens 20 mainly corrects the full-field aberration and the field curvature of the marginal field in the far-infrared optical system 100; at the same time, ensuring that the second aspherical lens 30 can provide the main optical power in the far-infrared optical system 100.
[0047] The far-infrared optical system 100 provided in this application has better imaging quality, and the total optical length of the far-infrared optical system 100 is smaller, making the far-infrared optical system 100 have a smaller volume. The number of lenses in the far-infrared optical system 100 is smaller, resulting in a lower cost of the far-infrared optical system 100. Moreover, the cost of a single meta-lens 20 during mass production in the far-infrared optical system 100 is lower, which can further reduce the cost of the far-infrared optical system 100.
[0048] Please refer to Figure 1 , in some embodiments, the edge of the object side surface of the first aspherical lens 10 has an inflection point, and the edge of the image side surface of the first aspherical lens 10 has an inflection point. The object side surface of the second aspherical lens 30 bulges towards the object side, the image side surface of the second aspherical lens 30 bulges towards the object side, and the paraxial region of the image side surface of the second aspherical lens 30 has an inflection point. In this application, the paraxial region on a certain surface of a lens refers to the region enclosed by a circle with the optical axis S as the center and a certain length as the radius on the corresponding surface of the lens.
[0049] Please refer to Figure 5 , in some embodiments, the edge of the object side surface of the first aspherical lens 10 has an inflection point, and the edge of the image side surface of the first aspherical lens 10 has an inflection point. The object side surface of the second aspherical lens 30 bulges towards the object side, and the image side surface of the second aspherical lens 30 bulges towards the object side.
[0050] Please refer to Figure 9 , in some embodiments, the object side surface of the second aspherical lens 30 bulges towards the image side, and the paraxial region of the object side surface of the second aspherical lens 30 has an inflection point. The image side surface of the second aspherical lens 30 bulges towards the image side.
[0051] In some embodiments, the micro-nano structure 220 is disposed on the object side surface of the substrate 210.
[0052] In some embodiments, the micro-nano structure 220 is disposed on the image side surface of the substrate 210.
[0053] In some embodiments, the micro-nano structure 220 is provided on both the object-side surface and the image-side surface of the substrate 210, so that the metalens 20 has a high degree of design freedom.
[0054] In some embodiments, the micro-nano structure 220 is a positive micro-nano structure.
[0055] In some embodiments, the micro-nano structure 220 is a negative micro-nano structure.
[0056] In some embodiments, the micro-nano structure 220 is provided with a single layer, so that the processing technology of the metalens 20 is compatible with the existing semiconductor processing technology, which is convenient for the processing and manufacturing of the metalens 20.
[0057] In some embodiments, the micro-nano structure 220 is provided with two or more layers, so that the metalens 20 has a large and expected optical power.
[0058] For the metalens 20, the surface of the substrate 210 where the micro-nano structure 220 is disposed, the positive / negative of the micro-nano structure 220, and the number of layers of the micro-nano structure 220 can be freely combined, as long as the metalens 20 has the expected performance.
[0059] In some embodiments, the phase distribution of the metalens 20 satisfies one of the following formulas:
[0060]
[0061]
[0062] where r is the distance from the center of the metalens 20 to any micro-nano structure 220, λ is the central wavelength of the working band of the metalens 20, is the phase constant, (x, y) is the two-dimensional coordinate of the surface of the metalens 20, a i 、b i 、a ij 、b ij are all real coefficients, N is the number of phase coefficient terms, and f m is the focal length of the metalens 20.
[0063] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula Two: Among them, FOV (Field Of View, abbreviated as FOV) is the maximum field of view angle of the far-infrared optical system 100, and the unit of FOV is degree. TTL (Total Track Length, abbreviated as TTL) is the total optical length of the far-infrared optical system 100, f is the effective focal length of the far-infrared optical system 100, and f m is the focal length of the superlens 20. The dimensions of TTL, f, and f m are the same, all being length units, such as millimeters.
[0064] The lower limit of conditional formula two reflects the maximum total optical length that the far-infrared optical system 100 can achieve under the action of the superlens 20; the upper limit of conditional formula two reflects the minimum total optical length that the far-infrared optical system 100 can achieve under the action of the superlens 20.
[0065] In some embodiments, the far-infrared optical system 100 satisfies conditional formula three: Among them, L is the distance between the image side of the second aspherical lens 30 and the image plane B of the far-infrared optical system 100 on the optical axis S. f is the effective focal length of the far-infrared optical system 100, and f a1 is the focal length of the first aspherical lens 10, and f a2 is the focal length of the second aspherical lens 30. The dimensions of L, f, f a1 , f a2 are the same, all being length units, such as millimeters.
[0066] The upper limit of conditional formula three reflects the minimum optical back focal length that the far-infrared optical system 100 can achieve when satisfying the imaging performance, and the upper limit of conditional formula three reflects the maximum optical back focal length that the far-infrared optical system 100 can achieve when satisfying the imaging performance. Conditional formula three limits the optical back focal length range of the far-infrared optical system 100 when satisfying the imaging performance, and compressing the length of the optical back focal length is beneficial to compressing the total optical length of the far-infrared optical system 100.
[0067] In some embodiments, the far-infrared optical system 100 satisfies conditional formula four: Among them, r1 is half of the effective diameter of the object side of the first aspherical lens 10, r2 is half of the effective diameter of the image side of the first aspherical lens 10. In this application, the effective diameter of the lens refers to the diameter of the largest light-passing area on the corresponding surface of the lens. R1 is the curvature radius of the object side of the first aspherical lens 10, and R2 is the curvature radius of the image side of the first aspherical lens 10. f a1 is the focal length of the first aspherical lens 10, CT1 is the central thickness of the first aspherical lens 10, that is, CT1 is the thickness of the first aspherical lens 10 on the optical axis S. r1, r2, R1, R2, f a1The dimensions of CT1 are the same, both being length units, such as millimeters.
[0068] The lower limit of Conditional Formula Four represents the case of the maximum optical power that the first aspherical lens 10 can occupy by itself in the far-infrared optical system 100, and the upper limit of Conditional Formula Four represents the case of the minimum optical power that the first aspherical lens 10 can occupy by itself in the far-infrared optical system 100.
[0069] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula Five: where r3 is half of the effective diameter of the object side surface of the second aspherical lens 30, r4 is half of the effective diameter of the image side surface of the second aspherical lens 30, R3 is the curvature radius of the object side surface of the second aspherical lens 30, R4 is the curvature radius of the image side surface of the second aspherical lens 30, and f a2 is the focal length of the second aspherical lens 30. CT2 is the central thickness of the second aspherical lens 30, that is, CT2 is the thickness of the second aspherical lens 30 on the optical axis S. r3, r4, R3, R4, f a2 and CT2 have the same dimensions, all being length units, such as millimeters.
[0070] The lower limit of Conditional Formula Five represents the case of the maximum optical power that the second aspherical lens 30 can occupy by itself in the far-infrared optical system 100, and the upper limit of Conditional Formula Five represents the case of the minimum optical power that the second aspherical lens 30 can occupy by itself in the far-infrared optical system 100.
[0071] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula Six: where is the maximum phase difference of the meta-lens 20, and its unit is rad. f m is the focal length of the meta-lens 20, r m is half of the effective diameter of the meta-lens 20, CT m is the central thickness of the meta-lens 20, that is, CT m is the thickness of the meta-lens 20 on the optical axis S. f m and r m and CT m have the same dimensions, all being length units, such as millimeters.
[0072] The smaller the value of Conditional Formula Six, the greater the role played by the meta-lens 20 itself in light control. The upper limit of Conditional Formula Six can ensure that the meta-lens 20 can play a role in the far-infrared optical system 100 to reduce chromatic aberration or other aberrations. The lower limit of Conditional Formula Six corresponds to the case where the meta-lens 20 plays the greatest role in light control in the far-infrared optical system 100.
[0073] In some embodiments, the far-infrared optical system 100 satisfies Conditional Equation Seven: where f is the effective focal length of the far-infrared optical system 100, and EPD (Entrance Pupil Diameter, abbreviated as EPD) is the entrance pupil diameter of the far-infrared optical system 100. f and EPD have the same dimension, both being length units, such as millimeters.
[0074] Conditional Equation Seven reflects the range of the F-number of the far-infrared optical system 100. From Conditional Equation Seven, it can be seen that the far-infrared optical system 100 has a relatively large entrance pupil diameter, a relatively large light passing amount, and can collect as much energy entering the far-infrared optical system 100 as possible under the condition that the imaging detector adapted to the far-infrared optical system 100 has a low response to light energy, thereby ensuring excellent imaging quality.
[0075] In some embodiments, the far-infrared optical system 100 satisfies Conditional Equation Eight: where SAG2 is the sag of the image side of the first aspherical lens 10 at the target point, and the target point is the point where the vertical distance between the intersection of the image side of the first aspherical lens 10 and the optical axis S is equal to half of the effective diameter of the image side of the first aspherical lens 10; r2 is half of the effective diameter of the image side of the first aspherical lens 10. SAG2 and r2 have the same dimension, both being length units, such as millimeters.
[0076] The lower limit of Conditional Equation Eight can ensure that the image side of the first aspherical lens 10 has a certain curvature, and the upper limit of Conditional Equation Eight can ensure that the image side of the first aspherical lens 10 has good processability to reduce the processing difficulty.
[0077] Please refer to Figure 1 、 Figure 5 and Figure 9 , in some embodiments, the far-infrared optical system 100 further includes a diaphragm 40. The diaphragm 40 is used to control the light passing amount of the far-infrared optical system 100 to ensure that the far-infrared optical system 100 can work effectively and generate high-quality images. The diaphragm 40 is disposed between any two adjacent lenses, or the diaphragm 40 is disposed on the object side of the first aspherical lens 10. Specifically, the position where the diaphragm 40 is disposed satisfies any one of the following conditions:
[0078] (1) The diaphragm 40 is located on the object side of the first aspherical lens 10 and is spaced apart from the first aspherical lens 10;
[0079] (2) The diaphragm 40 is located on the object side of the first aspherical lens 10 and is disposed in contact with the object side surface of the first aspherical lens 10;
[0080] (3) The aperture stop 40 is located between the first aspherical lens 10 and the metalens 20, and the aperture stop 40 is arranged in contact with the image side surface of the first aspherical lens 10;
[0081] (4) The aperture stop 40 is located between the first aspherical lens 10 and the metalens 20, and the aperture stop 40 is arranged at intervals from both the first aspherical lens 10 and the metalens 20;
[0082] (5) The aperture stop 40 is located between the first aspherical lens 10 and the metalens 20, and the aperture stop 40 is arranged in contact with the object side surface of the metalens 20;
[0083] (6) The aperture stop 40 is located between the metalens 20 and the second aspherical lens 30, and the aperture stop 40 is arranged in contact with the image side surface of the metalens 20;
[0084] (7) The aperture stop 40 is located between the metalens 20 and the second aspherical lens 30, and the aperture stop 40 is arranged at intervals from both the metalens 20 and the second aspherical lens 30;
[0085] (8) The aperture stop 40 is located between the metalens 20 and the second aspherical lens 30, and the aperture stop 40 is arranged in contact with the object side surface of the second aspherical lens 30.
[0086] Please refer to Figure 1 、 Figure 5 and Figure 9 again. In some embodiments, the far-infrared optical system 100 further includes a protective glass 50. The protective glass 50 is located between the second aspherical lens 30 and the image plane B, and the protective glass 50 is arranged close to the image plane B. The protective glass 50 is used to protect the imaging detector matched with the far-infrared optical system 100 to reduce the probability of damage to the imaging detector.
[0087] The far-infrared optical system 100 provided by this application has the following advantages:
[0088] (1) The total optical length (TTL) is less than 17.5 mm;
[0089] (2) The MTF (Modulation Transfer Function, abbreviated as MTF, modulation transfer function) of the 0.9 field of view at 42 lp / mm is greater than 0.34, and the cost is relatively low;
[0090] (3) The distortion is less than 1%.
[0091] This application exemplarily provides 3 far-infrared optical systems 100 that meet the usage requirements in 3 embodiments. Next, the far-infrared optical systems 100 provided by each embodiment of this application will be introduced in detail.
[0092] Embodiment 1
[0093] Figure 1 Shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Embodiment 1. Figure 1 The mid- and far-infrared optical system 100 sequentially includes, along the optical axis S from the object surface A to the image surface B: a first aspherical lens 10, a diaphragm 40, a metalens 20, a second aspherical lens 30, and a protective glass 50. Among them, the micro-nano structure 220 is provided on the object side surface of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Embodiment 1 are shown in Table 1-1.
[0094] Table 1-1. Some parameters of the far-infrared optical system 100 provided in Embodiment 1
[0095] Parameter Data Total Track Length (TTL) 17.0152 mm Maximum Field Angle (2ω) 21.9° F - number 0.75 Effective Focal Length 10 mm Operating Wavelength Band Far - Infrared (8μm - 12μm)
[0096] As can be seen from Table 1-1, the working band of the far-infrared optical system 100 is far-infrared light with a wavelength range of 8 μm to 12 μm, and the total optical length of the far-infrared optical system 100 is relatively short, only 17.0152 mm. Therefore, the volume of the far-infrared optical system 100 provided in Embodiment 1 is relatively small. The F-number of the far-infrared optical system 100 is 0.75, which can greatly increase the light input of the far-infrared optical system 100, and can collect as much energy as possible entering the far-infrared optical system 100 when the imaging detector has a low response to light energy, thereby ensuring excellent imaging quality.
[0097] Along the direction of the optical axis S from the object surface A to the image surface B, starting from the first aspherical lens 10, each surface in the far-infrared optical system 100 is numbered, and after summarizing the parameters of each surface, the following Table 1-2 is obtained.
[0098] Table 1-2. Parameters of each surface in the far-infrared optical system 100 provided in Embodiment 1
[0099] Surface Number Surface Type Radius of Curvature (mm) Thickness (mm) Refractive Index of Material 1 Aspheric Surface 9.06E+00 2.84E+00 2.78 2 Aspheric Surface 8.06E+00 3.30E+00 - 3 Aperture Stop Infinity 1.76E+00 - 4 Structural Surface Infinity 3.00E-01 3.42 5 Spherical Surface Infinity 9.52E-02 - 6 Aspheric Surface 1.74E+01 2.18E+00 2.78 7 Aspheric Surface -1.64E+02 5.94E+00 - 8 Spherical Surface Infinity 5.00E-01 3.42 9 Spherical Surface Infinity 1.00E-01 - 10 Image Plane Infinity - -
[0100] For each surface in Table 1-2, surface 1 is the object side surface of the first aspherical lens 10, and surface 2 is the image side surface of the first aspherical lens 10. Surface 3 is the diaphragm 40, surface 4 is the object side surface of the metalens 20. Since the micro-nano structure 220 is provided on the object side surface of the substrate 210, surface 4 is denoted as the structural surface, and surface 5 is the image side surface of the metalens 20. Surface 6 is the object side surface of the second aspherical lens 30, and surface 7 is the image side surface of the second aspherical lens 30. Surface 8 is the object side surface of the protective glass 50, surface 9 is the image side surface of the protective glass 50, and surface 10 is the image surface B.
[0101] As can be seen from Table 1-2, Surface 1 is an aspheric surface. The radius of curvature of Surface 1 is 9.06E+00 mm. The distance between Surface 1 and Surface 2 is 2.84E+00 mm. The refractive index of the material between Surface 1 and Surface 2 is 2.78. Surface 2 is an aspheric surface. The radius of curvature of Surface 2 is 8.06E+00 mm. The distance between Surface 2 and Surface 3 is 3.30E+00 mm. The material between Surface 2 and Surface 3 is air. The radius of curvature of Surface 3 is infinite, that is, Surface 3 is a plane. The distance between Surface 3 and Surface 4 is 1.76E+00 mm. The material between Surface 3 and Surface 4 is air. The radius of curvature of Surface 4 is infinite, that is, Surface 4 is a plane. The distance between Surface 4 and Surface 5 is 3.00E-01 mm. The refractive index of the material between Surface 4 and Surface 5 is 3.42. The radius of curvature of Surface 5 is infinite, that is, Surface 5 is a plane. The distance between Surface 5 and Surface 6 is 9.52E-02 mm. The material between Surface 5 and Surface 6 is air. Surface 6 is an aspheric surface. The radius of curvature of Surface 6 is 1.74E+01 mm. The distance between Surface 6 and Surface 7 is 2.18E+00 mm. The refractive index of the material between Surface 6 and Surface 7 is 2.78. Surface 7 is an aspheric surface. The radius of curvature of Surface 7 is -1.64E+02 mm. The distance between Surface 7 and Surface 8 is 5.94E+00 mm. The material between Surface 7 and Surface 8 is air. The radius of curvature of Surface 8 is infinite, that is, Surface 8 is a plane. The distance between Surface 8 and Surface 9 is 5.00E-01 mm. The refractive index of the material between Surface 8 and Surface 9 is 3.42. The radius of curvature of Surface 9 is infinite, that is, Surface 9 is a plane. The distance between Surface 9 and Surface 10 is 1.00E-01 mm. The material between Surface 9 and Surface 10 is air.
[0102] Surfaces 1, 2, 6, and 7 are even aspheric surfaces, and their surface profiles satisfy the following relationship:
[0103]
[0104] Among them, Z(r) is the distance sag from the vertex of the aspheric surface along the optical axis S direction at the position with height r. c is the surface curvature of the aspheric surface, c = 1 / R, and R is the radius of curvature of the aspheric surface. k is the conic coefficient. A, B, C, D... are the aspheric coefficients. The values of k, A, B, C, D... for Surfaces 1, 2, 6, and 7 can be queried from Table 1-3.
[0105] Table 1-3. Coefficients of Each Order of Even Aspheric Surfaces in the Far-Infrared Optical System 100 Provided in Embodiment 1
[0106]
[0107] Please refer to Table 1-3. Taking Surface 1 as an example, its k is -2.9E-01, A is 1.4E-04, B is -1.1E-05, C is -8.0E-08, D is 8.1E-09, E is -4.1E-10, F is 8.5E-12, and G is -6.8E-14. The values of k, A, B, C, D... for Surface 3, Surface 6, and Surface 7 can be obtained by querying Table 1-3 and will not be elaborated here one by one.
[0108] Please refer to Figure 2 , Figure 2 which shows the MTF field curve graph of the far-infrared optical system 100 provided in Embodiment 1. Figure 2 The abscissa in Figure 2 is the X-axis field of view, and its unit is degree; Figure 2 lists the sagittal curve S1 and meridional curve T1 of the MTF varying with the field of view at a spatial frequency of 21 lp / mm, and the sagittal curve S2 and meridional curve T2 of the MTF varying with the field of view at a spatial frequency of 42 lp / mm. From Figure 2 it can be seen that within the full field of view (10.95°), the MTF is greater than 0.38, and the imaging quality of the far-infrared optical system 100 is excellent.
[0109] Please refer to Figure 3 , Figure 3 which shows the field curvature graph of the far-infrared optical system 100 provided in Embodiment 1. Figure 3 The horizontal axis in Figure 3 is the field curvature, and its unit is millimeter; Figure 3 The vertical axis in Figure 3 is the Y-axis field of view, and its unit is degree. S1 in
[0110] Please refer to Figure 4 , Figure 4 which shows the distortion graph of the far-infrared optical system 100 provided in Embodiment 1. Figure 4 The horizontal axis in Figure 4 is the distortion, and its unit is percentage; Figure 4The distortion curves of the far-infrared optical system 100 under far-infrared light of 8 μm, 10 μm, and 12 μm are respectively shown. Since the three curves almost completely overlap, in this embodiment, the three curves are not distinguished. From Figure 4 It can be seen that the maximum distortion of the far-infrared optical system 100 provided in Embodiment 1 is -0.79%, and the distortion is small, meeting the requirements for distortion in the excellent imaging quality standard.
[0111] Embodiment 2
[0112] Figure 5 The schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Embodiment 2 is shown. Figure 5 The mid- and far-infrared optical system 100 sequentially includes, along the optical axis S from the object surface A to the image surface B: a first aspherical lens 10, a diaphragm 40, a metasurface lens 20, a second aspherical lens 30, and a protective glass 50, where the micro-nano structure 220 is provided on the object side surface of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Embodiment 2 are shown in Table 2-1.
[0113] Table 2-1. Some parameters of the far-infrared optical system 100 provided in Embodiment 2
[0114] Parameter Data Total Track Length (TTL) 17.0473 mm Maximum Field Angle (2ω) 23° F - number 0.75 Effective Focal Length 10 mm Operating Wavelength Band Far - Infrared (8μm - 12μm)
[0115] As can be seen from Table 2-1, the working band of the far-infrared optical system 100 is far-infrared light from 8 μm to 12 μm, and the overall optical length of the far-infrared optical system 100 is relatively short, only 17.0473 mm. Therefore, the volume of the far-infrared optical system 100 provided in Embodiment 2 is relatively small. The F number of the far-infrared optical system 100 is 0.75, which can greatly increase the light input amount of the far-infrared optical system 100 and collect as much energy as possible entering the far-infrared optical system 100 under the condition that the imaging detector has a low response to light energy, thereby ensuring excellent imaging quality.
[0116] Along the direction of the optical axis S from the object surface A to the image surface B, starting from the first aspherical lens 10, each surface in the far-infrared optical system 100 is numbered, and after summarizing the parameters of each surface, the following Table 2-2 is obtained.
[0117] Table 2-2. Parameters of each surface in the far-infrared optical system 100 provided in Embodiment 2
[0118] Surface Number Surface Type Radius of Curvature (mm) Thickness (mm) Refractive Index of Material 1 Aspheric Surface 9.23E+00 2.64E+00 2.78 2 Aspheric Surface 8.66E+00 3.94E+00 - 3 Aperture Stop Infinity 9.73E-02 - 4 Structural Surface Infinity 3.00E-01 3.42 5 Spherical Surface Infinity 1.88E+00 - 6 Aspheric Surface 1.22E+01 2.15E+00 2.78 7 Aspheric Surface 4.29E+01 5.44E+00 - 8 Spherical Surface Infinity 5.00E-01 3.42 9 Spherical Surface Infinity 1.00E-01 - 10 Image Plane Infinity - -
[0119] For the analysis of each surface in Table 2-2, reference can be made to Embodiment 1, and this embodiment will not analyze it again.
[0120] Surfaces 1, 2, 6, and 7 are even aspherical surfaces, and their surface profiles satisfy the following relationship:
[0121]
[0122] Among them, Z(r) is the distance sagitta from the vertex of the aspheric surface along the optical axis S direction at the position with height r; c is the surface curvature of the aspheric surface, c = 1 / R, and R is the radius of curvature of the aspheric surface; k is the conic coefficient; A, B, C, D... are the aspheric coefficients. The values of k, A, B, C, D... of surfaces 2, 3, 6, and 7 can be obtained by querying Table 2-3.
[0123] Table 2-3. Coefficients of each order of even aspheric surfaces in the far-infrared optical system 100 provided in Embodiment 2
[0124]
[0125] The values of k, A, B, C, D... of surfaces 1, 2, 6, and 7 can be obtained by querying Table 2-3, and will not be elaborated one by one in this embodiment.
[0126] Please refer to Figure 6 , Figure 6 which shows the MTF field curve graph of the far-infrared optical system 100 provided in Embodiment 2. Figure 6 The abscissa in Figure 6 is the X-axis field of view, and its unit is degree; Figure 6 The ordinate in Figure 6 is the MTF value. Figure 6 lists the sagittal curve S1 and meridional curve T1 of the MTF varying with the field of view at a spatial frequency of 21 lp / mm, and the sagittal curve S2 and meridional curve T2 of the MTF varying with the field of view at a spatial frequency of 42 lp / mm. It can be seen from Figure 6 that within the full field of view (11.5°), the MTF is greater than 0.38, and the imaging quality of the far-infrared optical system 100 is excellent.
[0127] Please refer to Figure 7 , Figure 7 which shows the field curvature graph of the far-infrared optical system 100 provided in Embodiment 2. Figure 7 The horizontal axis in Figure 7 is the field curvature, and its unit is millimeter; Figure 7 The vertical axis in Figure 7 is the Y-axis field of view, and its unit is degree. Figure 7 In Figure 7It can be seen that the maximum field curvature of the far-infrared optical system 100 in the sagittal direction under far-infrared light of 10 μm is 0.061 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction under far-infrared light of 10 μm is 0.037 mm. The field curvature is small, meeting the requirements for field curvature in the excellent imaging quality standard.
[0128] Please refer to Figure 8 , Figure 8 which shows the distortion diagram of the far-infrared optical system 100 provided in Embodiment 2. Figure 8 In Figure 8 , the horizontal axis is distortion, and its unit is percentage; Figure 8 In Figure 8 , the distortion curves of the far-infrared optical system 100 under far-infrared light of 8 μm, 10 μm, and 12 μm are respectively shown. Since the three curves almost completely overlap, therefore, the three curves are not distinguished in this embodiment. It can be seen from
[0129] Embodiment 3
[0130] Figure 9 which shows the schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Embodiment 3. Figure 9 In
[0131] the far-infrared optical system 100 along the optical axis S from the object surface A to the image surface B sequentially includes: a diaphragm 40, a first aspherical lens 10, a meta-lens 20, a second aspherical lens 30, and a protective glass 50. Among them, the micro-nano structure 220 is provided on the object side surface of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Embodiment 3 are shown in Table 3-1.
[0131] Table 3-1. Some parameters of the far-infrared optical system 100 provided in Embodiment 3
[0132] Parameter Data Total Track Length (TTL) 17.3 mm Maximum Field Angle (2ω) 23.2° F - number 0.75 Effective Focal Length 9.82 mm Operating Wavelength Band Far - Infrared (8μm - 12μm)
[0133] It can be seen from Table 3-1 that the working band of the far-infrared optical system 100 is far-infrared light from 8 μm to 12 μm, and the total optical length of the far-infrared optical system 100 is relatively short, only 17.3 mm. Therefore, the volume of the far-infrared optical system 100 provided in Embodiment 3 is relatively small. The F number of the far-infrared optical system 100 is 0.75, which can greatly increase the light input of the far-infrared optical system 100 and collect as much energy entering the far-infrared optical system 100 as possible under the condition that the imaging detector has a low response to light energy, thereby ensuring excellent imaging quality.
[0134] In the direction from the object plane A to the image plane B along the optical axis S, starting from the first aspherical lens 10, each surface in the far-infrared optical system 100 is numbered, and after summarizing the parameters of each surface, the following Table 3-2 is obtained.
[0135] Table 3-2. Parameters of each surface in the far-infrared optical system 100 provided in Embodiment 3
[0136]
[0137]
[0138] The values of k, A, B, C, D... of Surface 1, Surface 2, Surface 6, and Surface 7 can be obtained by querying Table 3-3, and will not be elaborated one by one in this embodiment.
[0139] Surface 2, Surface 3, Surface 6, and Surface 7 are even aspherical surfaces, and their surface profiles satisfy the following relationship:
[0140]
[0141] Among them, Z(r) is the distance sagitta from the vertex of the aspherical surface at the position with height r along the optical axis S direction of the aspherical surface; c is the surface curvature of the aspherical surface, c = 1 / R, and R is the radius of curvature of the aspherical surface; k is the conic coefficient; A, B, C, D... are aspherical coefficients. The values of k, A, B, C, D... of Surface 1, Surface 2, Surface 6, and Surface 7 can be obtained by querying Table 3-3.
[0142] Table 3-3. Coefficients of each order of even aspherical surfaces in the far-infrared optical system 100 provided in Embodiment 3
[0143]
[0144] The values of k, A, B, C, D... of Surface 1, Surface 2, Surface 6, and Surface 7 can be obtained by querying Table 3-3, and will not be elaborated one by one in this embodiment.
[0145] Please refer to Figure 10 , Figure 10 which shows the MTF field curve graph of the far-infrared optical system 100 provided in Embodiment 3. Figure 10 The abscissa in Figure 10 is the X-axis field of view, and its unit is degree; Figure 10 The ordinate in Figure 10 lists the sagittal curve S1 and meridional curve T1 of the MTF varying with the field of view at a spatial frequency of 21 lp / mm, and the sagittal curve S2 and meridional curve T2 of the MTF varying with the field of view at a spatial frequency of 42 lp / mm. From Figure 10It can be seen that within the full field of view (11.6°), the MTF is greater than 0.34, and the imaging quality of the far-infrared optical system 100 is excellent.
[0146] Please refer to Figure 11 , Figure 11 which shows the field curvature diagram of the far-infrared optical system 100 provided in Embodiment 3. Figure 11 In the horizontal axis is the field curvature, and its unit is millimeter; Figure 11 in the vertical axis is the Y-axis field of view, and its unit is degree. Figure 11 In it, S1 is the field curvature of the far-infrared light with a wavelength of 8 μm in the sagittal direction, T1 is the field curvature of the far-infrared light with a wavelength of 8 μm in the meridional direction; S2 is the field curvature of the far-infrared light with a wavelength of 10 μm in the sagittal direction, T2 is the field curvature of the far-infrared light with a wavelength of 10 μm in the meridional direction; S3 is the field curvature of the far-infrared light with a wavelength of 12 μm in the sagittal direction, T3 is the field curvature of the far-infrared light with a wavelength of 12 μm in the meridional direction. It can be seen from Figure 11 that the maximum field curvature of the far-infrared optical system 100 in the sagittal direction under the far-infrared light of 10 μm is 0.014 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction under the far-infrared light of 10 μm is 0.048 mm. The field curvature is small, meeting the requirements for field curvature in the excellent imaging quality standard.
[0147] Please refer to Figure 12 , Figure 12 which shows the distortion diagram of the far-infrared optical system 100 provided in Embodiment 3. Figure 12 In it, the horizontal axis is the distortion, and its unit is percentage; Figure 12 in the vertical axis is the Y-axis field of view, and its unit is degree. Figure 12 In it, the distortion curves of the far-infrared optical system 100 under the far-infrared light of 8 μm, 10 μm, and 12 μm are respectively shown. Since the three curves almost completely overlap, therefore, the three curves are not distinguished in this embodiment. It can be seen from Figure 12 that the maximum distortion of the far-infrared optical system 100 provided in Embodiment 3 is -0.76%, and the distortion is small, meeting the requirements for distortion in the excellent imaging quality standard.
[0148] After summarizing the various parameters of the far-infrared optical system 100 provided in the above three embodiments, Table 4 as shown below is obtained. The display of Table 4 is mainly used to illustrate that the various conditions met by the far-infrared optical system 100 provided in this application are all experimentally verified and supported.
[0149] Table 4. Various parameters of the far-infrared optical system 100 provided in each embodiment
[0150]
[0151]
[0152] The present application also provides a far-infrared optical lens, which includes an imaging detector (not shown in the figure) and the above-mentioned far-infrared optical system 100. For the specific architecture of the far-infrared optical system 100, reference can be made to the above text and will not be elaborated here. The imaging detector is disposed on the image plane B of the far-infrared optical system 100. The imaging detector includes, but is not limited to, CMOS (Complementary Metal Oxide Semiconductor), abbreviated as CMOS, complementary metal oxide semiconductor) and CCD (Charge Coupled Device, abbreviated as CCD, charge coupled device).
[0153] After considering the specification and practicing the utility model disclosed herein, those skilled in the art will readily conceive of other embodiments of the present application. The present application is intended to cover any variations, uses, or adaptations of the present application, which follow the general principles of the present application and include common general knowledge or conventional technical means in the technical field not disclosed in the present application. The specification and examples are only regarded as exemplary, and the true scope and spirit of the present application are pointed out by the appended claims.
Claims
1. A far-infrared optical system, characterized in that, The far-infrared optical system sequentially includes, from the object side to the image side along the optical axis: a first aspherical lens, a metalens, and a second aspherical lens; the first aspherical lens has a positive optical power, the object side surface of the first aspherical lens bulges towards the object side, and the image side surface of the first aspherical lens bulges towards the object side; the metalens has a positive optical power, and the metalens includes: a substrate and a micro-nano structure, and the micro-nano structure is disposed on the object side surface and / or the image side surface of the substrate; the second aspherical lens has a positive optical power; Among them, the far-infrared optical system satisfies: f m > f a1 > f a2 , where the f m is the focal length of the metalens, and the f a1 is the focal length of the first aspherical lens, and the f a2 is the focal length of the second aspherical lens.
2. The far-infrared optical system according to claim 1, wherein The far-infrared optical system satisfies the following: wherein, the FOV is the maximum field of view angle of the far-infrared optical system, the TTL is the total optical length of the far-infrared optical system, and the f is the effective focal length of the far-infrared optical system.
3. The far-infrared optical system according to claim 1, characterized in that The far-infrared optical system satisfies the following: Wherein, L is the distance between the image side surface of the second aspherical lens and the image plane of the far-infrared optical system on the optical axis, and f is the effective focal length of the far-infrared optical system.
4. The far-infrared optical system according to claim 1, wherein, The far-infrared optical system satisfies the following: Wherein, r1 is half of the effective diameter of the object side surface of the first aspherical lens, r2 is half of the effective diameter of the image side surface of the first aspherical lens, R1 is the curvature radius of the object side surface of the first aspherical lens, R2 is the curvature radius of the image side surface of the first aspherical lens, and CT1 is the central thickness of the first aspherical lens.
5. The far-infrared optical system according to claim 1, characterized in that, The far-infrared optical system satisfies the following: Wherein, r3 is half of the effective diameter of the object side surface of the second aspherical lens, r4 is half of the effective diameter of the image side surface of the second aspherical lens, R3 is the curvature radius of the object side surface of the second aspherical lens, R4 is the curvature radius of the image side surface of the second aspherical lens, and CT2 is the central thickness of the second aspherical lens.
6. The far-infrared optical system according to claim 1, characterized in that, The far-infrared optical system satisfies: wherein, the is the maximum phase difference of the metalens, the r m is half of the effective diameter of the metalens, and the CT m is the central thickness of the metalens.
7. The far-infrared optical system according to claim 1, characterized in that The far-infrared optical system satisfies: wherein, f is the effective focal length of the far-infrared optical system, and EPD is the entrance pupil diameter of the far-infrared optical system.
8. The far-infrared optical system according to claim 1, characterized in that, The far-infrared optical system satisfies: Wherein, SAG2 is the sag of the image side surface of the first aspherical lens at the target point, and the target point is the point where the vertical distance between the intersection of the image side surface of the first aspherical lens and the optical axis is equal to half of the effective diameter of the image side surface of the first aspherical lens; r2 is half of the effective diameter of the image side surface of the first aspherical lens.
9. The far-infrared optical system according to any one of claims 1-8, characterized in that, The far-infrared optical system further includes a diaphragm, and the diaphragm is disposed between any two adjacent lenses; or, the diaphragm is disposed on the object side of the first aspherical lens.
10. A far-infrared optical lens, characterized in that, The far-infrared optical lens includes: an imaging detector and the far-infrared optical system according to any one of claims 1-9; the imaging detector is disposed on the image plane of the far-infrared optical system.