Far infrared optical system and far infrared optical lens

Abstract

The utility model discloses a far infrared optical system and a far infrared optical lens. The far infrared optical system sequentially comprises a first refractor, a super lens and a second refractor from an object side to an image side along an optical axis, the object side surface and the image side surface of the first refraction lens protrude towards the object side; the focal power of the super lens is positive, the super lens comprises a substrate and a micro-nano structure, and at least one of the object side surface and the image side surface of the substrate is provided with the micro-nano structure; the focal power of the second refraction lens is positive, the object side face of the second refraction lens protrudes towards the object side, and the image side face of the second refraction lens protrudes towards the image side. The far infrared optical system meets the following conditions: phi m < phi a1 < phi a2, phi a1 is the focal power of the first refractor, phi m is the focal power of the super lens, and phi a2 is the focal power of the second refractor. The far infrared optical system satisfies the following conditions: # imgabs0 # fa1 is the focal length of the first refractor, fm is the focal length of the super lens, and fa2 is the focal length of the second refractor. The far infrared optical system has the advantages of being good in imaging quality, good in machinability and low in production cost.

Description

Technical Field

[0001] The present application relates to the field of optical systems, and in particular to a far-infrared optical system and a far-infrared optical lens. Background Art

[0002] In the field of far-infrared optical systems, in order to improve imaging quality, the surface design of lenses is usually optimized, which may result in the problem of excessive curvature of some lenses in the far-infrared optical system. Excessive curvature of the lenses may lead to difficulty in lens processing and low processing yield, which in turn leads to poor processability and high cost of the far-infrared optical system, which is not conducive to the mass production of far-infrared optical systems. Utility Model Content

[0003] In response to the above technical problems, the embodiments of the present application provide a far-infrared optical system and a far-infrared optical lens, aiming to provide a far-infrared optical system and a far-infrared optical lens with good imaging quality, good processability and low production cost.

[0004] According to one aspect of an embodiment of the present application, a far-infrared optical system is disclosed, and the far-infrared optical system includes, in order from the object side to the image side along the optical axis: a first refractive lens, a super lens, and a second refractive lens; the object side surface of the first refractive lens is convex toward the object side, and the image side surface of the first refractive lens is convex toward the object side; the optical power of the super lens is positive, the super lens includes a substrate and a micro-nano structure, and at least one of the object side surface of the substrate and the image side surface of the substrate is provided with the micro-nano structure; the optical power of the second refractive lens is positive, the object side surface of the second refractive lens is convex toward the object side, and the image side surface of the second refractive lens is convex toward the image side;

[0005] The far-infrared optical system satisfies: |Φ m |<|Φ a1 |<|Φ a2 |, where the Φ a1 is the focal length of the first refractive lens, the Φ m is the optical power of the metalens, the Φ a2 is the focal power of the second refractive lens;

[0006] The far-infrared optical system meets the following requirements: Among them, the f a1 is the focal length of the first refractive lens, the f m is the focal length of the superlens, and the f a2 is the focal length of the second refractive lens.

[0007] In some embodiments, the far-infrared optical system satisfies: Wherein, the CT1 is the center thickness of the first refractive lens, the CT3 is the center thickness of the second refractive lens, the D1 is the maximum effective diameter of the first refractive lens, and the D3 is the maximum effective diameter of the second refractive lens.

[0008] In some embodiments, the far-infrared optical system satisfies: Among them, the C 13 is the distance between the object side surface of the first refractive lens and the image side surface of the second refractive lens on the optical axis, the TTL is the total optical length of the far-infrared optical system, and the FOV is the maximum field of view angle of the far-infrared optical system.

[0009] In some embodiments, the far-infrared optical system satisfies: Wherein, D1 is the maximum effective diameter of the first refractive lens, D2 is the maximum effective diameter of the super lens, and D3 is the maximum effective diameter of the second refractive lens.

[0010] In some embodiments, the far-infrared optical system satisfies: Wherein, the ET1 is the edge thickness of the first refractive lens, and the ET3 is the edge thickness of the second refractive lens.

[0011] In some embodiments, the far-infrared optical system satisfies: Among them, f is the effective focal length of the far-infrared optical system, n is the refractive index of the first refractive lens, FNO is the aperture number of the far-infrared optical system, and R1 is the curvature radius of the object side of the first refractive lens.

[0012] In some embodiments, the far-infrared optical system satisfies: Among them, Sag1 is the projection of the distance between the first point and the second point on the optical axis, the first point is the intersection of the object side surface of the first refractive lens and the optical axis, and the second point is the position where the maximum effective diameter of the first refractive lens is located; if the second point is located on the object side of the first point, Sag1 is a negative value, and if the second point is located on the image side of the first point, Sag1 is a positive value; Sag2 is the projection of the distance between the third point and the fourth point on the optical axis, the third point is the intersection of the image side surface of the first refractive lens and the optical axis, and the fourth point is the position where the maximum effective diameter of the image side surface of the first refractive lens is located; if the fourth point is located on the object side of the third point, Sag2 is a negative value, and if the fourth point is located on the image side of the third point, Sag2 is a positive value.

[0013] In some embodiments, the far-infrared optical system satisfies: Among them, Sag2 is the projection of the distance between the third point and the fourth point on the optical axis, the third point is the intersection of the image side surface of the first refractive lens and the optical axis, and the fourth point is the position of the maximum effective diameter of the image side surface of the first refractive lens; if the fourth point is located on the object side of the third point, Sag2 is a negative value, and if the fourth point is located on the image side of the third point, Sag2 is a positive value; Sag3 is the projection of the distance between the fifth point and the sixth point on the optical axis, the fifth point is the intersection of the object side surface of the second refractive lens and the optical axis, and the sixth point is the position of the maximum effective diameter of the object side surface of the second refractive lens; if the sixth point is located on the object side of the fifth point, Sag3 is a negative value, and if the sixth point is located on the image side of the fifth point, Sag3 is a positive value; R2 is the radius of curvature of the image side surface of the first refractive lens, and R3 is the radius of curvature of the object side surface of the second refractive lens.

[0014] In some embodiments, the far-infrared optical system satisfies: The CT1 is the center thickness of the first refractive lens, and the CT3 is the center thickness of the second refractive lens.

[0015] In some embodiments, the far-infrared optical system satisfies: Wherein, R3 is the curvature radius of the object side surface of the second refractive lens, and R4 is the curvature radius of the image side surface of the second refractive lens.

[0016] In some embodiments, the far-infrared optical system further includes an aperture, and the aperture is located on the object side of the first refractive lens; or, the aperture is located between any two adjacent lenses.

[0017] A second aspect of an embodiment of the present application provides a far-infrared optical lens, which includes: an image detector and a far-infrared optical system as described in any one of the above items.

[0018] The far-infrared optical system provided by the present application includes: a first refractive lens, a super lens, and a second refractive lens in order from the object side to the image side along the optical axis; the object side surface of the first refractive lens is convex to the object side, and the image side surface of the first refractive lens is convex to the object side; the optical focal length of the super lens is positive, the super lens includes a substrate and a micro-nano structure, and at least one of the object side surface of the substrate and the image side surface of the substrate is provided with a micro-nano structure; the optical focal length of the second refractive lens is positive, the object side surface of the second refractive lens is convex to the object side, and the image side surface of the second refractive lens is convex to the image side. The far-infrared optical system satisfies: |Φ m |<|Φ a1 |<|Φ a2 |, where Φ a1is the focal power of the first refractive lens, Φ m is the focal power of the metalens, Φ a2 is the focal length of the second refractive lens. The far-infrared optical system satisfies: Among them, f a1 is the focal length of the first refractive lens, f m is the focal length of the metalens, f a2 is the focal length of the second refractive lens. The far-infrared optical system provided by the present application performs chromatic aberration correction through a super lens, performs aberration compensation of the entire field of view and spherical aberration correction of the edge field of view through a second refractive lens, so that the far-infrared optical system has good imaging quality. In addition, the far-infrared optical system has good processability while having good imaging quality by reasonably allocating the optical focal length, which can reduce the processing difficulty of each lens in the far-infrared optical system. Since the super lens can be produced through semiconductor technology, the cost of a single super lens is low in mass production, so that the far-infrared optical system also has the advantage of low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0020] Figure 1 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0021] Figure 2 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0022] Figure 3 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0023] Figure 4 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0024] Figure 5 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0025] Figure 6 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0026] Figure 7 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0027] Figure 8 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0028] Fig. 9 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0029] Fig.10 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0030] Fig.11 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0031] Fig.12 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0032] Fig.13 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0033] Fig.14 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0034] Fig.15 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0035] Fig.16 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0036] Fig.17 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0037] Fig.18 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0038] Fig.19 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0039] Fig. 20 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0040] Fig.21 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0041] Fig. 22 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0042] Fig.23A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0043] Fig.24 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0044] Reference numerals

[0045] 100. Far infrared optical system;

[0046] 10. a first refractive lens;

[0047] 20. Super lens; 210. Substrate; 220. Micro-nano structure;

[0048] 30. a second refractive lens;

[0049] 40. Shutter window;

[0050] 50. Window glass;

[0051] 60. Aperture;

[0052] A. Object plane; B. Image plane; C. Optical axis. DETAILED DESCRIPTION

[0053] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of 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 comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0054] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other modules, components, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application obscure.

[0055] See also Figure 1 , Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of a far-infrared optical system 100 in an embodiment of the present application, wherein the optical axis C is the center line of the light beam. Figure 1In the figure, the object to be measured is located on the left side of the leftmost lens, that is, the object side is located 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 located 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 C is consistent with the direction from the object side to the image side along the optical axis C.

[0056] In the present application, the side of each optical element close to the object side is its object side, and the side of each optical element close to the image side is its image side. For example, the side of the first refractive lens 10 close to the object side is the image side of the first refractive lens 10. The surface of each optical element close to the object side is its object side surface, and the surface of each optical element close to the image side is its image side surface. For example, the object side surface of the first refractive lens 10 is the surface of the first refractive lens 10 close to the object side.

[0057] The far-infrared optical system 100 includes a first refractive lens 10, a super lens 20 and a second refractive lens 30, which are sequentially arranged along an optical axis C from an object side to an image side.

[0058] The optical power of the first refractive lens 10 can be positive or negative. Specifically, in some embodiments, the optical power of the first refractive lens 10 is positive; in other embodiments, the optical power of the first refractive lens 10 is negative. The object side surface of the first refractive lens 10 is convex to the object side, and the image side surface of the first refractive lens 10 is convex to the object side.

[0059] The optical focal length of the superlens 20 is positive. The superlens 20 includes a substrate 210 and a micro-nano structure 220. At least one of the object side surface of the substrate 210 and the image side surface of the substrate 210 is provided with the micro-nano structure 220, and the micro-nano structure 220 is a sub-wavelength structure. According to the phase modulation method adopted, the corresponding phase modulation formula can be adaptively used to configure the various parameters of the micro-nano structure 220, so that the superlens 20 can achieve the corresponding optical performance, so that the superlens 20 has the expected deflection ability for far-infrared light.

[0060] The second refractive lens 30 has a positive power, an object side surface of the second refractive lens 30 is convex toward the object side, and an image side surface of the second refractive lens 30 is convex toward the image side. One of the first refractive lens 10 and the second refractive lens 30 is an aspherical lens, and the other of the first refractive lens 10 and the second refractive lens 30 is a spherical lens.

[0061] The far-infrared optical system 100 satisfies the conditional formula 1: |Φ m |<|Φ a1 |<|Φ a2 |, where Φ a1 is the focal length of the first refractive lens 10, Φ m is the focal power of the superlens 20, Φa2 is the focal length of the second refractive lens 30 , and the conditional expression 1 is used to reasonably distribute the focal length of the optical system.

[0062] The far-infrared optical system 100 satisfies conditional formula 2: Among them, f a1 is the focal length of the first refractive lens 10, f m is the focal length of the superlens 20, f a2 is the focal length of the second refractive lens 30. m 、f a1 、f a2 have the same dimension, which is a unit of length, such as millimeter.

[0063] Conditional formula 2 reflects the overall distribution of the optical power of the far-infrared optical system 100. Specifically, conditional formula 2 can ensure that the optical power provided by the metalens 20 and the first refractive lens 10 in the far-infrared optical system 100 is much smaller than the optical power of the second refractive lens 30, indicating that the main function of the metalens 20 is chromatic aberration correction, and the main function of the second refractive lens 30 is aberration compensation of the full field of view and spherical aberration correction of the edge field of view. The upper limit of conditional formula 2 can ensure that the metalens 20 and the first refractive lens 10 can play a greater role in regulating light. The lower limit of conditional formula 2 can avoid the metalens 20 providing a large optical power. If the optical power of the metalens 20 is too large, it will bring greater dispersion to the far-infrared optical system 100, that is, the lower limit of conditional formula 2 can avoid the metalens 20 introducing a large chromatic aberration.

[0064] The far-infrared optical system 100 provided by the present application performs chromatic aberration correction through the metalens 20, performs aberration compensation of the entire field of view and spherical aberration correction of the edge field of view through the second refractive lens 30, so that the far-infrared optical system 100 has good imaging quality. In addition, the far-infrared optical system 100 has good processability under the premise of having good imaging quality by reasonably allocating the optical focal length, which can reduce the processing difficulty of each lens in the far-infrared optical system 100. Since the metalens 20 can be produced by semiconductor technology, the cost of a single metalens 20 is low in mass production, so that the far-infrared optical system 100 also has the advantage of low cost.

[0065] Furthermore, in some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 3: f m 、f a1 、f a2 The parameters represented can refer to the second embodiment, and will not be repeated here. Conditional formula three is used to more accurately allocate the optical focal length of the far-infrared optical system 100, and can ensure that the super lens 20 and the first refractive lens 10 can play a greater role in aberration correction.

[0066] See also Figure 1 and Fig.19 In some embodiments, the micro-nano structure 220 is disposed on a surface of the substrate 210 close to the object side.

[0067] See also Fig.13 In some embodiments, the micro-nano structure 220 is disposed on a surface of the substrate 210 close to the image side.

[0068] See also Figure 7 In some embodiments, the surface of the substrate 210 close to the object side and the surface of the substrate 210 close to the image side are both provided with a micro-nano structure 220, so that the superlens 20 has a higher degree of design freedom.

[0069] In some embodiments, the micro-nano structure 220 is a positive micro-nano structure.

[0070] In some embodiments, the micro-nano structure 220 is a negative micro-nano structure.

[0071] In some embodiments, the micro-nano structure 220 is provided with a layer to make the processing technology of the superlens 20 compatible with the existing semiconductor processing technology, which can facilitate the processing and manufacturing of the superlens 20.

[0072] In some embodiments, the micro-nano structure 220 has two or more layers, so that the superlens 20 has a larger and expected optical focal length.

[0073] For the superlens 20, the position of the micro-nano structure 220, the positive and negative sides 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 superlens 20 has the expected performance.

[0074] In some embodiments, the phase distribution of the metalens 20 satisfies the following formula:

[0075]

[0076]

[0077] Where r is the distance from the center of the superlens to any micro-nanostructure, λ is the central wavelength of the working band of the superlens, is the phase constant, (x, y) is the two-dimensional coordinate of the surface of the metalens, a i , b i 、a ij , b ij are all real coefficients, N is the number of phase coefficients, f m is the focal length of the metalens.

[0078] In some embodiments, the first refractive lens 10 is a spherical lens, and the second refractive lens 30 is an aspherical lens, so that the far-infrared optical system 100 has good imaging quality and low production cost.

[0079] In some embodiments, the first refractive lens 10 is an aspherical lens, and the second refractive lens 30 is a spherical lens, so that the far-infrared optical system 100 has good imaging quality and low production cost.

[0080] In some embodiments, the first refractive lens 10 and the second refractive lens 30 are both aspherical lenses, which can further control the aberration of the far-infrared optical system 100, so that the far-infrared optical system 100 has better imaging quality.

[0081] In some embodiments, the far-infrared optical system 100 satisfies Condition 4: Wherein, CT1 is the center thickness of the first refractive lens 10. In the present application, the center thickness of the lens refers to the thickness of the lens on the optical axis C, that is, CT1 is the thickness of the first refractive lens 10 on the optical axis C. CT3 is the center thickness of the second refractive lens 30. D1 is the maximum effective diameter of the first refractive lens 10. In the present application, the maximum effective diameter of the lens refers to the diameter of the maximum light-transmitting area of ​​the lens, that is, D1 is the diameter of the maximum light-transmitting area of ​​the first refractive lens 10. D3 is the maximum effective diameter of the second refractive lens 30. CT1, CT3, D1, and D3 have the same dimension, which is a length unit, such as millimeters.

[0082] The upper limit of conditional formula 4 is used to control the volume and weight of the far-infrared optical system 100 to ensure that the aperture of the far-infrared optical system 100 is not too large; at the same time, the upper limit of conditional formula 4 can reduce the amount of lens material used, thereby achieving the control of the weight of the optical system. The lower limit of conditional formula 4 can ensure that the far-infrared optical system 100 has sufficient relative illumination, and is conducive to improving the spherical aberration and field curvature of the far-infrared optical system 100.

[0083] In some embodiments, the far-infrared optical system 100 satisfies Condition 5: Among them, C 13 is the distance between the object side surface of the first refractive lens 10 and the image side surface of the second refractive lens 30 on the optical axis C, TTL (Total Track Length, abbreviated as TTL) is the total optical length of the far-infrared optical system 100, C 13 , TTL have the same dimension, both are length units, such as millimeters. FOV (Field of View, referred to as FOV) is the maximum field of view of the far-infrared optical system 100, and its unit is degree.

[0084] The upper limit of conditional formula 5 can ensure that the far-infrared optical system 100 has a small volume while leaving enough optical back focal length to leave enough space for image sensors and structural parts, which can facilitate the smooth assembly of the corresponding lenses of the far-infrared optical system 100. The lower limit of conditional formula 5 can ensure that the far-infrared optical system 100 has good imaging performance and a small volume.

[0085] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 6: Wherein, D1 is the maximum effective diameter of the first refractive lens 10, D2 is the maximum effective diameter of the superlens 20, and D3 is the maximum effective diameter of the second refractive lens 30. D1, D2, and D3 have the same dimension, which is a length unit, such as millimeters.

[0086] The upper limit of conditional formula six is ​​used to control the aperture of the thicker first refractive lens 10 and the aperture of the metalens 20, which can reduce the amount of lens material used for the first refractive lens 10 and the metalens 20, thereby reducing the cost of the far-infrared optical system 100. At the same time, it is beneficial to the processing of the metalens 20 and the assembly of the lens corresponding to the far-infrared optical system 100. The lower limit of conditional formula six can ensure that the far-infrared optical system 100 has sufficient relative illumination while controlling the aperture of the far-infrared optical system 100.

[0087] In some embodiments, the far-infrared optical system 100 satisfies conditional equation 7: ET1 is the edge thickness of the first refractive lens 10, and ET3 is the edge thickness of the second refractive lens 30. ET1 and ET3 have the same dimension, which is a length unit, such as millimeters.

[0088] The upper limit of conditional expression 7 can prevent the second refractive lens 30 from being too thin, so that the second refractive lens 30 has good processability, and at the same time, ensure that the second refractive lens 30 has sufficient strength, so that the second refractive lens 30 has good assembly reliability. The lower limit of conditional expression 7 improves the field curvature of the far-infrared optical system 100 while ensuring that the thickness of the first refractive lens 10 is not too large.

[0089] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 8: Wherein, f is the effective focal length of the far-infrared optical system 100, and n is the refractive index of the first refractive lens 10. FNO is the aperture number of the far-infrared optical system 100, that is, the F number. R1 is the radius of curvature of the object side surface of the first refractive lens 10. f and R1 have the same dimension, both of which are length units, such as millimeters.

[0090] Conditional formula eight indicates that the far-infrared optical system 100 can enable an image detector with a pixel number of 640×512 and a pixel size of 12 microns to have excellent imaging quality within the system parameter condition range. It is worth mentioning that the specification of the image detector adapted by the far-infrared optical system 100 provided in the present application is not limited to the specification of a pixel number of 640×512 and a pixel size of 12 microns.

[0091] In some embodiments, the far-infrared optical system 100 satisfies Condition 9: Wherein, Sag1 is the projection of the distance between the first point and the second point on the optical axis C, the first point is the intersection of the object side surface of the first refractive lens 10 and the optical axis C, the second point is the position of the maximum effective diameter of the object side surface of the first refractive lens 10, that is, the second point is the point with the longest vertical distance from the optical axis C in the maximum effective area (maximum light transmission area) of the object side surface of the first refractive lens 10. The value of Sag1 can be positive or negative. If the second point is located on the object side of the first point, Sag1 is a negative value, and if the second point is located on the image side of the first point, Sag1 is a positive value. Sag2 is the projection of the distance between the third point and the fourth point on the optical axis C, the third point is the intersection of the image side surface of the first refractive lens 10 and the optical axis C, the fourth point is the position of the maximum effective diameter of the image side surface of the first refractive lens 10, that is, the fourth point is the point with the longest vertical distance from the optical axis C in the maximum effective area (maximum light transmission area) of the image side surface of the first refractive lens 10. The value of Sag2 can be positive or negative. If the fourth point is on the object side of the third point, Sag2 is negative. If the fourth point is on the image side of the third point, Sag2 is positive. Sag1 and Sag2 have the same dimension, which is a length unit, such as millimeters.

[0092] The upper limit of Conditional Formula 9 can prevent the shape of the first refractive lens 10 from being too curved, which is beneficial to the manufacture and molding of the first refractive lens 10. The lower limit of Conditional Formula 9 can ensure that the first refractive lens 10 can play a greater role in correcting the edge aberration.

[0093] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 10: Wherein, Sag2 is the projection of the distance between the third point and the fourth point on the optical axis C, the third point is the intersection of the image side surface of the first refractive lens 10 and the optical axis C, the fourth point is the position of the maximum effective diameter of the image side surface of the first refractive lens 10, that is, the fourth point is the point with the longest vertical distance from the optical axis C in the maximum effective area (maximum light transmission area) of the image side surface of the first refractive lens 10. The value of Sag2 can be positive or negative. If the fourth point is located on the object side of the third point, Sag2 is a negative value, and if the fourth point is located on the image side of the third point, Sag2 is a positive value. Sag3 is the projection of the distance between the fifth point and the sixth point on the optical axis C, the fifth point is the intersection of the object side surface of the second refractive lens 30 and the optical axis C, the sixth point is the position of the maximum effective diameter of the object side surface of the second refractive lens 30, that is, the sixth point is the point with the longest vertical distance from the optical axis C in the maximum effective area (maximum light transmission area) of the object side surface of the second refractive lens 30. The value of Sag3 can be positive or negative. If the sixth point is located on the object side of the fifth point, Sag3 is a negative value. If the sixth point is located on the image side of the fifth point, Sag3 is a positive value. R2 is the radius of curvature of the image side surface of the first refractive lens 10, and R3 is the radius of curvature of the object side surface of the second refractive lens 30. Sag2, Sag3, R2, and R3 have the same dimension, which is a length unit, such as millimeters.

[0094] Conditional formula 10 is used to control the surface shapes of the first refractive lens 10 and the second refractive lens 30, which can prevent the image side surface of the first refractive lens 10 from being too concave, improve the processability of the first refractive lens 10 and the second refractive lens 30, and ensure that the far-infrared optical system 100 has sufficient relative illumination. In addition, conditional formula 10 can make the light propagation between the first refractive lens 10 and the second refractive lens 30 smoother, and reduce the tolerance sensitivity of the far-infrared optical system 100.

[0095] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 11: Wherein, CT1 is the center thickness of the first refractive lens 10, f a1 is the focal length of the first refractive lens 10. CT3 is the center thickness of the second refractive lens 30, f a2 is the focal length of the second refractive lens 30. a1 , CT3, f a2 have the same dimension, which is a unit of length, such as millimeter.

[0096] The upper limit of conditional formula 11 can be used to limit the volume of the first refractive lens 10, and the lower limit of conditional formula 11 is used to ensure that the first refractive lens 10 and the third refractive lens can play a greater role in field curvature compensation, thereby reducing the field curvature of the far-infrared optical system 100 to improve the imaging quality of the far-infrared optical system 100.

[0097] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 12: Wherein, R3 is the radius of curvature of the object side surface of the second refractive lens 30, and R4 is the radius of curvature of the image side surface of the second refractive lens 30. R3 and R4 have the same dimension, both of which are length units, such as millimeters.

[0098] Conditional formula twelve is used to control the aberration of the far-infrared optical system 100 . The far-infrared optical system 100 satisfying conditional formula twelve is beneficial to the correction of spherical aberration and field curvature by the second refractive lens 30 , and can improve the imaging quality of the far-infrared optical system 100 .

[0099] See also Figure 1 , Figure 7 , Fig.13 and Fig.19 In some embodiments, the far-infrared optical system 100 further includes an aperture 60, which is used to control the amount of light entering the far-infrared optical system 100, so as to ensure that the far-infrared optical system 100 can work effectively and generate high-quality images. The aperture 60 is disposed on the object side of the first refractive lens 10, or the aperture 60 is disposed between any two adjacent lenses. It should be noted that the "lens" in this application refers to a lens that has a modulating effect on light, and does not include other sheet-like optical elements.

[0100] In some embodiments, the aperture 60 is located at the object side of the first refractive lens 10 , and the aperture 60 is spaced apart from the first refractive lens 10 , that is, the aperture 60 has a preset distance from the first refractive lens 10 .

[0101] In some embodiments, the aperture 60 is located at the object side of the first refractive lens 10 , and the aperture 60 is disposed in close contact with the object side surface of the first refractive lens 10 .

[0102] In some embodiments, the aperture 60 is located between the first refractive lens 10 and the metalens 20. Specifically:

[0103] (1) The aperture 60 is disposed on the image side surface of the first refractive lens 10, that is, the aperture 60 is disposed in contact with the image side surface of the first refractive lens 10;

[0104] (2) The aperture 60 is located between the first refractive lens 10 and the super lens 20, and the aperture 60 is spaced apart from the first refractive lens 10 and the super lens 20;

[0105] (3) The aperture 60 is disposed on the object side of the metalens 20, that is, the aperture 60 is disposed in contact with the object side of the metalens 20. In some embodiments, the aperture 60 is located between the metalens 20 and the second refractive lens 30, specifically:

[0106] (1) The aperture 60 is disposed on the image side surface of the super lens 20, that is, the aperture 60 is disposed in contact with the image side surface of the super lens 20;

[0107] (2) The aperture 60 is located between the super lens 20 and the second refractive lens 30, and the aperture 60 is spaced apart from the super lens 20 and the second refractive lens 30;

[0108] (3) The aperture 60 is disposed on the object side surface of the second refractive lens 30 , that is, the aperture 60 is disposed in contact with the object side surface of the second refractive lens 30 .

[0109] See also Figure 1 , Figure 7 , Fig.13 and Fig.19 In some embodiments, the far-infrared optical system 100 further includes a window glass 50 , which is located on a side of the second refractive lens 30 away from the superlens 20 , and the window glass 50 is used to protect the image detector of the lens corresponding to the far-infrared optical system 100 .

[0110] Please refer again Figure 1 , Figure 7 , Fig.13 and Fig.19 In some embodiments, the far-infrared optical system 100 further includes a shutter window 40, which is located between the window glass 50 and the second refractive lens 30. The shutter window 40 is used to protect the shutter of the lens corresponding to the far-infrared optical system 100 from being collided by structural parts, thereby preventing the shutter from being damaged.

[0111] The far-infrared optical system 100 provided by the present application has the following benefits:

[0112] (1) Total optical length (TTL) ≤ 23 mm;

[0113] (2) At 20°C, the MTF is greater than 0.26 at a cutoff frequency of 42 lp / mm within a 0.8 field of view;

[0114] (3) It has good heat elimination effect in the range of -40℃ to 80℃.

[0115] The present application exemplarily provides four far-infrared optical systems 100 that meet usage requirements in four embodiments. Next, the far-infrared optical systems 100 provided in the various embodiments of the present application are introduced in detail.

[0116] Example 1

[0117] Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 1. Figure 1The mid-to-far infrared optical system 100 includes, along the optical axis C from the object plane A to the image plane B, in sequence: an aperture 60, a first refractive lens 10, a super lens 20, a second refractive lens 30, a shutter window 40, and a window glass 50, wherein the first refractive lens 10 is an aspherical lens, the second refractive lens 30 is a spherical lens, and the micro-nano structure 220 is disposed on the object side of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Example 1 are shown in Table 1-1.

[0118] Table 1-1. Partial parameters of the far-infrared optical system 100 provided in Example 1

[0119] parameter data Total optical length (TTL) 22.309mm Maximum field of view (2ω) 43.5° F-number 1.2 Effective focal length 12.9mm Working band Far infrared (8um-12um)

[0120] As can be seen from Table 1-1, the operating band of the far-infrared optical system 100 is 8 microns to 12 microns. The F number of the far-infrared optical system 100 is 1.2, which can greatly increase the amount of light entering the far-infrared optical system 100, and collect as much energy entering the far-infrared optical system 100 as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.

[0121] Along the optical axis C from the object plane A to the image plane B, starting from the first refractive lens 10, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 1-2.

[0122] Table 1-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 1

[0123] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aperture unlimited -1.239 - 2 even aspherical surface 11.500 5.229 Chalcogenide glass 3 even aspherical surface 8.014 1.646 - 4 Spherical unlimited 0.300 silicon 5 Structural surface unlimited 2.205 - 6 Spherical 45.194 3.105 Chalcogenide glass 7 Spherical -24.068 6.949 - 8 Spherical unlimited 0.300 germanium 9 Spherical unlimited 1.000 - 10 Spherical unlimited 0.575 silicon 11 Spherical unlimited 1.000 - 12 Image plane unlimited - -

[0124] For each surface in Table 1-2, surface 1 is the aperture 60, surface 2 is the object side surface of the first refractive lens 10, and surface 3 is the image side surface of the first refractive lens 10. Surface 4 is the object side surface of the super lens 20, and surface 5 is the image side surface of the super lens 20. Surface 6 is the object side surface of the second refractive lens 30, and surface 7 is the image side surface of the second refractive lens 30. Surface 8 is the object side surface of the shutter window 40, and surface 9 is the image side surface of the shutter window 40. Surface 10 is the object side surface of the window glass 50, and surface 11 is the image side surface of the window glass 50. Surface 12 is the image plane B.

[0125] As can be seen from Table 1-2, the radius of curvature of surface 1 is infinite, that is, surface 1 is a plane, and the distance between surface 1 and surface 2 is -1.239 mm, where the negative sign in "-1.239" means that the vertex of the object side surface of the first refractive lens 10 protrudes from the aperture 60, and the material between surface 1 and surface 2 is air. Surface 2 is an even-order aspheric surface, the radius of curvature of surface 2 is 11.500 mm, the distance between surface 2 and surface 3 is 5.229 mm, and the material between surface 2 and surface 3 is chalcogenide glass. Surface 3 is an even-order aspheric surface, the radius of curvature of surface 3 is 8.014 mm, the distance between surface 3 and surface 4 is 1.646 mm, and 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 0.300 mm, and the material between surface 4 and surface 5 is silicon. The radius of curvature of surface 5 is infinite, that is, surface 5 is a plane. Since the micro-nano structure 220 is disposed on the image side of the substrate 210, surface 5 is recorded as the structural surface, the distance between surface 5 and surface 6 is 2.205 mm, and the material between surface 5 and surface 6 is air. Surface 6 is a spherical surface, and its radius of curvature is 45.194 mm. The distance between surface 6 and surface 7 is 3.105 mm, and the material between surface 6 and surface 7 is chalcogenide glass. Surface 7 is a spherical surface, and its radius of curvature is -24.068 mm. The distance between surface 7 and surface 8 is 6.949 mm, and 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 0.300 mm, and the material between surface 8 and surface 9 is germanium. 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 1.000 mm, and the material between surface 9 and surface 10 is air. The radius of curvature of surface 10 is infinite, that is, surface 10 is a plane, the distance between surface 10 and surface 11 is 0.575 mm, and the material between surface 10 and surface 11 is silicon. The radius of curvature of surface 11 is infinite, that is, surface 11 is a plane, the distance between surface 11 and surface 12 is 1.000 mm, and the material between surface 11 and surface 12 is air.

[0126] Surface 2 and surface 3 are both even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0127]

[0128] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis C; c is the curvature of the aspherical surface, c = 1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 2 and surface 3 can be obtained from Table 1-3.

[0129] Table 1-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 1

[0130]

[0131] From Table 1-3, we can see that the k of surface 2 is -0.092, A is -6.34E-05, B is 4.94E-06, C is -7.85E-07, D is 5.03E-08, E is -1.83E-09, F is 3.44E-11, and G is 0. The values ​​of k, A, B, C, D, etc. of surface 3 can be found in Table 1-3 with reference to surface 2, and will not be elaborated here.

[0132] See also Figure 2 , Figure 2 The MTF (Modulation Transfer Function, MTF for short) field of view curve of the far-infrared optical system 100 provided in Example 1 at 20° C. is shown. Figure 2 The horizontal axis in is the image height, and its unit is millimeters. Figure 2 The mid-horizontal axis measures the field of view using image height; Figure 2 The vertical axis is the MTF value. Figure 2 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Figure 2 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.24, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0133] See also Figure 3 , Figure 3 The MTF field curve of the far-infrared optical system 100 provided in Example 1 at -40°C is shown. Figure 3 The horizontal axis in is the image height, and its unit is millimeters. Figure 3 The central horizontal axis measures the field of view using image height; Figure 3 The vertical axis is the MTF value. Figure 3 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Figure 3It can be seen that at a spatial frequency of 42lp / mm, within a field of view of 0.9 (4.428 mm image height), the MTF is greater than 0.2, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0134] See also Figure 4 , Figure 4 The MTF field curve of the far-infrared optical system 100 provided in Example 1 at 80° C. is shown. Figure 4 The horizontal axis in is the image height, and its unit is millimeters. Figure 4 The central horizontal axis measures the field of view using image height; Figure 4 The vertical axis is the MTF value. Figure 4 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Figure 4 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.18, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0135] Depend on Figures 2 to 4 It can be seen that within the range of -40°C to 80°C, at the same spatial frequency, the MTF value of the far-infrared optical system 100 provided in Example 1 is less affected by temperature, indicating that the far-infrared optical system 100 provided in Example 1 has a good athermal effect.

[0136] See also Figure 5 , Figure 5 1 shows a field curvature diagram of the far-infrared optical system 100 provided in Example 1, Figure 5 The central horizontal axis is the field curvature, which is in millimeters; Figure 5 The vertical axis is the field of view angle, and its unit is degree. Figure 5 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Figure 5 It can be seen that within the full field of view, the maximum field curvature of the far-infrared optical system 100 in the sagittal direction at the central wavelength is 0.28 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction at the central wavelength is 0.57 mm, and the field curvature is relatively small.

[0137] See also Figure 6 , Figure 61 shows a distortion diagram of the far-infrared optical system 100 provided in Example 1, Figure 6 The horizontal axis in is the distortion, and its unit is percentage; Figure 6 The vertical axis is the field of view angle, and its unit is degree. Figure 6 FIG. 1 shows the distortion of the far-infrared optical system 100 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns. Figure 6 The three curves in are too close together, so they are not distinguished. Figure 6 It can be seen that within the full field of view, the maximum distortion of the far-infrared optical system 100 is -5.8%, which is relatively small.

[0138] Example 2

[0139] Figure 7 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 2. Figure 7 The mid-to-far infrared optical system 100 includes, along the optical axis C from the object plane A to the image plane B, in sequence: an aperture 60, a first refractive lens 10, a super lens 20, a second refractive lens 30, a shutter window 40, and a window glass 50, wherein the first refractive lens 10 is an aspherical lens, the second refractive lens 30 is a spherical lens, and the micro-nano structure 220 is arranged on the object side and the image side of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Example 2 are shown in Table 2-1.

[0140] Table 2-1. Partial parameters of the far-infrared optical system 100 provided in Example 2

[0141] parameter data Total optical length (TTL) 22.003mm Maximum field of view (2ω) 43.9° F-number 1.2 Effective focal length 13.3mm Working band Far infrared (8um-12um)

[0142] As can be seen from Table 2-1, the operating band of the far-infrared optical system 100 is 8 microns to 12 microns. The F number of the far-infrared optical system 100 is 1.2, which can greatly increase the amount of light entering the far-infrared optical system 100 and collect as much energy entering the far-infrared optical system 100 as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.

[0143] Along the optical axis C from the object plane A to the image plane B, starting from the first refractive lens 10, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 2-2.

[0144] Table 2-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 2

[0145] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aperture unlimited -1.651 - 2 even aspherical surface 9.943 5.000 Chalcogenide glass 3 even aspherical surface 7.228 2.130 - 4 Spherical unlimited 0.300 silicon 5 Structural surface unlimited 2.961 - 6 Spherical 23.400 3.687 Chalcogenide glass 7 Spherical -58.343 6.850 - 8 Spherical unlimited 0.575 germanium 9 Spherical unlimited 0.100 - 10 Spherical unlimited 0.300 silicon 11 Spherical unlimited 0.100 - 12 Image plane unlimited - -

[0146] The analysis of each surface in Table 2-2 can refer to Example 1, which will not be described in detail in this example.

[0147] Surface 2 and surface 3 are both even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0148]

[0149] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis C; c is the curvature of the aspherical surface, c = 1 / R, R is the radius of curvature of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 2 and surface 3 can be obtained from Table 2-3.

[0150] Table 2-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 2

[0151]

[0152] For the analysis of Table 2-3, please refer to Example 1, which will not be described in detail in this example.

[0153] See also Figure 8 , Figure 8 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at 20° C. is shown. Figure 8 The horizontal axis in is the image height, and its unit is millimeters. Figure 8 The central horizontal axis measures the field of view using image height; Figure 8 The vertical axis is the MTF value. Figure 8 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Figure 8 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.21, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0154] See also Fig. 9 , Fig. 9 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at -40°C is shown. Fig. 9 The horizontal axis in is the image height, and its unit is millimeters. Fig. 9 The central horizontal axis measures the field of view using image height; Fig. 9 The vertical axis is the MTF value. Fig. 9The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Fig. 9 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.21, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0155] See also Fig.10 , Fig.10 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at 80° C. is shown. Fig.10 The horizontal axis in is the image height, and its unit is millimeters. Fig.10 The central horizontal axis measures the field of view using image height; Fig.10 The vertical axis is the MTF value. Fig.10 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Fig.10 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.19, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0156] Depend on Figures 8 to 10 It can be seen that within the range of -40℃ to 80℃, at the same spatial frequency,

[0157] The MTF value of the far-infrared optical system 100 provided in Example 2 is less affected by temperature, indicating that the far-infrared optical system 100 provided in Example 2 has a good athermal effect.

[0158] See also Fig.11 , Fig.11 2 shows a field curvature diagram of the far-infrared optical system 100 provided in Example 2, Fig.11 The central horizontal axis is the field curvature, which is in millimeters; Fig.11 The vertical axis is the field of view angle, and its unit is degree. Fig.11 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Fig.11It can be seen that within the full field of view, the maximum field curvature of the far-infrared optical system 100 in the sagittal direction at the central wavelength is 0.05 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction at the central wavelength is 0.14 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0159] See also Fig.12 , Fig.12 1 shows a distortion diagram of the far-infrared optical system 100 provided in Example 2, Fig.12 The horizontal axis in is the distortion, and its unit is percentage; Fig.12 The vertical axis is the field of view angle, and its unit is degree. Fig.12 FIG. 1 shows the distortion of the far-infrared optical system 100 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns. Fig.12 The three curves in are too close together, so they are not distinguished. Fig.12 It can be seen that within the full field of view, the maximum distortion of the far-infrared optical system 100 is -8.6%, which is relatively small.

[0160] Example 3

[0161] Fig.13 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 3. Fig.13 The mid-to-far infrared optical system 100 includes, along the optical axis C from the object plane A to the image plane B, in sequence: an aperture 60, a first refractive lens 10, a super lens 20, a second refractive lens 30, a shutter window 40, and a window glass 50, wherein the first refractive lens 10 is an aspherical lens, the second refractive lens 30 is a spherical lens, and the micro-nano structure 220 is arranged on the image side of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Example 3 are shown in Table 3-1.

[0162] Table 3-1. Partial parameters of the far-infrared optical system 100 provided in Example 3

[0163] parameter data Total optical length (TTL) 22.005mm Maximum field of view (2ω) 43.9° F-number 1.2 Effective focal length 13.3mm Working band Far infrared (8um-12um)

[0164] As can be seen from Table 3-1, the operating band of the far-infrared optical system 100 is 8 microns to 12 microns. The F number of the far-infrared optical system 100 is 1.2, which can greatly increase the amount of light entering the far-infrared optical system 100 and collect as much energy as possible entering the far-infrared optical system 100 when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.

[0165] Along the optical axis C from the object plane A to the image plane B, starting from the first refractive lens 10, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 3-2.

[0166] Table 3-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 3

[0167] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aperture unlimited -1.821 - 2 even aspherical surface 9.301 4.280 Chalcogenide glass 3 even aspherical surface 7.005 3.528 - 4 Spherical unlimited 0.300 silicon 5 Structural surface unlimited 2.271 - 6 Spherical 24.712 3.436 Chalcogenide glass 7 Spherical -59.084 7.115 - 8 Spherical unlimited 0.575 germanium 9 Spherical unlimited 0.100 - 10 Spherical unlimited 0.300 silicon 11 Spherical unlimited 0.100 - 12 Image plane unlimited - -

[0168] The analysis of each surface in Table 3-2 can refer to Example 1, which will not be described in detail in this example.

[0169] Surface 2 and surface 3 are both even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0170]

[0171] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis C; c is the curvature of the aspherical surface, c = 1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 2 and surface 3 can be obtained from Table 3-3.

[0172] Table 3-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 3

[0173]

[0174] For the analysis of Table 3-3, please refer to Example 1, which will not be described in detail in this example.

[0175] See also Fig.14 , Fig.14 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at 20° C. is shown. Fig.14 The horizontal axis in is the image height, and its unit is millimeters. Fig.14 The central horizontal axis measures the field of view using image height; Fig.14 The vertical axis is the MTF value. Fig.14 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Fig.14 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.28, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0176] See also Fig.15 , Fig.15 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at -40°C is shown. Fig.15The horizontal axis in is the image height, and its unit is millimeters. Fig.15 The central horizontal axis measures the field of view using image height; Fig.15 The vertical axis is the MTF value. Fig.15 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Fig.15 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.21, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0177] See also Fig.16 , Fig.16 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at 80° C. is shown. Fig.16 The horizontal axis in is the image height, and its unit is millimeters. Fig.16 The central horizontal axis measures the field of view using image height; Fig.16 The vertical axis is the MTF value. Fig.16 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Fig.16 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.2, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0178] Depend on Figures 14 to 16 It can be seen that within the range of -40°C to 80°C, at the same spatial frequency, the MTF value of the far-infrared optical system 100 provided in Example 3 is less affected by temperature, indicating that the far-infrared optical system 100 provided in Example 3 has a good athermal effect.

[0179] See also Fig.17 , Fig.17 1 shows a field curvature diagram of the far-infrared optical system 100 provided in Example 1, Fig.17 The central horizontal axis is the field curvature, which is in millimeters; Fig.17 The vertical axis is the field of view angle, and its unit is degree. Fig.17S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Fig.17 It can be seen that within the full field of view, the maximum field curvature of the far-infrared optical system 100 in the sagittal direction at the central wavelength is 0.03 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction at the central wavelength is 0.11 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0180] See also Fig.18 , Fig.18 1 shows a distortion diagram of the far-infrared optical system 100 provided in Example 3, Fig.18 The horizontal axis in is the distortion, and its unit is percentage; Fig.18 The vertical axis is the field of view angle, and its unit is degree. Fig.18 FIG. 1 shows the distortion of the far-infrared optical system 100 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns. Fig.18 The three curves in are too close together, so they are not distinguished. Fig.18 It can be seen that within the full field of view, the maximum distortion of the far-infrared optical system 100 is -8.6%, which is relatively small.

[0181] Example 4

[0182] Fig.19 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 4. Fig.19 The mid-to-far infrared optical system 100 includes, along the optical axis C from the object plane A to the image plane B, in sequence: an aperture 60, a first refractive lens 10, a super lens 20, a second refractive lens 30, a shutter window 40, and a window glass 50, wherein the first refractive lens 10 is an aspherical lens, the second refractive lens 30 is a spherical lens, and the micro-nano structure 220 is disposed on the object side of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Example 4 are shown in Table 1-1.

[0183] Table 4-1. Partial parameters of the far-infrared optical system 100 provided in Example 4

[0184] parameter data Total optical length (TTL) 22.003mm Maximum field of view (2ω) 43.9° F-number 1.2 Effective focal length 13.3mm Working band Far infrared (8um-12um)

[0185] As can be seen from Table 4-1, the operating band of the far-infrared optical system 100 is 8 microns to 12 microns. The F number of the far-infrared optical system 100 is 1.2, which can greatly increase the amount of light entering the far-infrared optical system 100 and collect as much energy entering the far-infrared optical system 100 as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.

[0186] Along the optical axis C from the object plane A to the image plane B, starting from the first refractive lens 10, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 4-2.

[0187] Table 4-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 4

[0188] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aperture unlimited -1.750 - 2 even aspherical surface 9.639 4.668 Chalcogenide glass 3 even aspherical surface 7.181 4.191 - 4 Structural surface unlimited 0.300 silicon 5 Spherical unlimited 1.374 - 6 Spherical 24.214 3.681 Chalcogenide glass 7 Spherical -58.291 6.714 - 8 Spherical unlimited 0.575 germanium 9 Spherical unlimited 0.100 - 10 Spherical unlimited 0.300 silicon 11 Spherical unlimited 0.100 - 12 Image plane unlimited - -

[0189] The analysis of each surface in Table 4-2 can refer to Example 1, which will not be described in detail in this example.

[0190] Surface 2 and surface 3 are both even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0191]

[0192] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis C; c is the curvature of the aspherical surface, c = 1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 2 and surface 3 can be obtained from Table 4-3.

[0193] Table 4-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 4

[0194]

[0195] For the analysis of Table 4-3, please refer to Example 1, which will not be described in detail in this example.

[0196] See also Fig. 20 , Fig. 20 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at 20° C. is shown. Fig. 20 The horizontal axis in is the image height, and its unit is millimeters. Fig. 20 The central horizontal axis measures the field of view using image height; Fig. 20 The vertical axis is the MTF value. Fig. 20The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Fig. 20 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.18, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0197] See also Fig.21 , Fig.21 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at -40°C is shown. Fig.21 The horizontal axis in is the image height, and its unit is millimeters. Fig.21 The central horizontal axis measures the field of view using image height; Fig.21 The vertical axis is the MTF value. Fig.21 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Fig.21 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.22, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0198] See also Fig. 22 , Fig. 22 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at 80° C. is shown. Fig. 22 The horizontal axis in is the image height, and its unit is millimeters. Fig. 22 The central horizontal axis measures the field of view using image height; Fig. 22 The vertical axis is the MTF value. Fig. 22 The MTF of 10lp / mm spatial frequency with field of view changes in sagittal curve S1 and meridional curve T1, the MTF of 21lp / mm spatial frequency with field of view changes in sagittal curve S2 and meridional curve T2, the MTF of 42lp / mm spatial frequency with field of view changes in sagittal curve S3 and meridional curve T3. Fig. 22 It can be seen that at a spatial frequency of 42lp / mm, within the entire field of view, the MTF is greater than 0.2, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0199] Depend on Figure 20 to Figure 22It can be seen that within the range of -40°C to 80°C, at the same spatial frequency, the MTF value of the far-infrared optical system 100 provided in Example 4 is less affected by temperature, indicating that the far-infrared optical system 100 provided in Example 4 has a good athermal effect.

[0200] See also Fig.23 , Fig.23 1 shows a field curvature diagram of the far-infrared optical system 100 provided in Example 4, Fig.23 The central horizontal axis is the field curvature, which is in millimeters; Fig.23 The vertical axis is the field of view angle, and its unit is degree. Fig.23 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Fig.23 It can be seen that within the full field of view, the maximum field curvature of the far-infrared optical system 100 in the sagittal direction at the central wavelength is 0.04 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction at the central wavelength is 0.06 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0201] See also Fig.24 , Fig.24 1 shows a distortion diagram of the far-infrared optical system 100 provided in Example 4, Fig.24 The horizontal axis in is the distortion, and its unit is percentage; Fig.24 The vertical axis is the field of view angle, and its unit is degree. Fig.24 FIG. 1 shows the distortion of the far-infrared optical system 100 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns. Fig.24 The three curves in are too close together, so they are not distinguished. Fig.24 It can be seen that within the full field of view, the maximum distortion of the far-infrared optical system 100 is -8.4%, which is relatively small.

[0202] After summarizing the various parameters of the far-infrared optical system 100 provided by the above four embodiments, the following Table 5 is obtained. Table 5 is mainly used to illustrate that the various conditions satisfied by the far-infrared optical system 100 provided by the present application are all verified and supported by experiments.

[0203] Table 5. Parameters of the far-infrared optical system 100 provided in various embodiments

[0204]

[0205]

[0206] The present application also provides a far-infrared optical lens (not shown), which includes an imaging detector (not shown) and the above-mentioned far-infrared optical system 100. The architecture of the far-infrared optical system 100 can be referred to above and will not be repeated here. The imaging detector is arranged on the image plane B of the far-infrared optical system 100, and the imaging detector includes but is not limited to CMOS (Complementary Metal Oxide Semiconductor, referred to as CMOS, complementary metal oxide semiconductor) and CCD (Charge Coupled Device, referred to as CCD, charge coupled device).

[0207] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the utility model disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. A far-infrared optical system, characterized in that: The far-infrared optical system includes, in order from the object side to the image side along the optical axis: a first refractive lens, a super lens, and a second refractive lens; the object side surface of the first refractive lens is convex to the object side, and the image side surface of the first refractive lens is convex to the object side; the optical power of the super lens is positive, the super lens includes a substrate and a micro-nano structure, and at least one of the object side surface of the substrate and the image side surface of the substrate is provided with the micro-nano structure; the optical power of the second refractive lens is positive, the object side surface of the second refractive lens is convex to the object side, and the image side surface of the second refractive lens is convex to the image side; The far-infrared optical system satisfies: |Φ m |<|Φ a1 |<|Φ a2 |, where the Φ a1 is the focal length of the first refractive lens, the Φ m is the optical power of the metalens, the Φ a2 is the focal power of the second refractive lens; The far-infrared optical system meets the following requirements: Among them, the f a1 is the focal length of the first refractive lens, the f m is the focal length of the superlens, and the f a2 is the focal length of the second refractive lens.

2. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, the CT1 is the center thickness of the first refractive lens, the CT3 is the center thickness of the second refractive lens, the D1 is the maximum effective diameter of the first refractive lens, and the D3 is the maximum effective diameter of the second refractive lens.

3. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the C 13 is the distance between the object side surface of the first refractive lens and the image side surface of the second refractive lens on the optical axis, the TTL is the total optical length of the far-infrared optical system, and the FOV is the maximum field of view angle of the far-infrared optical system.

4. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, D1 is the maximum effective diameter of the first refractive lens, D2 is the maximum effective diameter of the super lens, and D3 is the maximum effective diameter of the second refractive lens.

5. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, the ET1 is the edge thickness of the first refractive lens, and the ET3 is the edge thickness of the second refractive lens.

6. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, f is the effective focal length of the far-infrared optical system, n is the refractive index of the first refractive lens, FNO is the aperture number of the far-infrared optical system, and R1 is the curvature radius of the object side of the first refractive lens.

7. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: The CT1 is the center thickness of the first refractive lens, and the CT3 is the center thickness of the second refractive lens.

8. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, R3 is the curvature radius of the object side surface of the second refractive lens, and R4 is the curvature radius of the image side surface of the second refractive lens.

9. The far-infrared optical system according to any one of claims 1 to 8, characterized in that: The far-infrared optical system further includes an aperture, and the aperture is located on the object side of the first refractive lens; or, the aperture is located between any two adjacent lenses.

10. A far-infrared optical lens, characterized in that: The far-infrared optical lens comprises: an image detector and a far-infrared optical system as described in any one of claims 1-9.

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