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 spherical lens, a super lens and an aspherical lens from an object side to an image side along an optical axis, the spherical lens has positive focal power, the curvature radius of the surface, close to the object side, of the spherical lens is a positive value, and the curvature radius of the surface, close to the image side, of the spherical lens is a positive value; the super lens has positive focal power; the aspheric lens has positive focal power, the surface, close to the object side, of the aspheric lens protrudes towards the image side, the surface, close to the image side, of the aspheric lens protrudes towards the image side, the refractive index of the aspheric lens is equal to that of the spherical lens, and the Abbe number of the aspheric lens is equal to that of the spherical lens. The astigmatism of the far infrared optical system is small, and the imaging quality is excellent. Meanwhile, the far infrared optical system provided by the utility model also has the advantages of small size and low cost.

Description

Technical Field

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

[0002] The far-infrared optical lens is a lens that uses far-infrared rays to form images. The far-infrared optical lens has the advantage of all-weather imaging.

[0003] In the prior art, some infrared optical lenses have serious astigmatism, resulting in average imaging quality. Astigmatism can be analyzed from the MTF (Modulation Transfer Function, MTF for short) field of view curve. Specifically, if the sagittal curve and the meridional curve at the same spatial frequency are relatively scattered, this will cause the focal plane positions of the center and edge of the image to be different. When the center is focused, the edge will become blurred, and when the edge is focused, the center will be blurred, resulting in average lens image quality. Utility Model Content

[0004] 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, which aim to solve the problem that some far-infrared optical lenses in the prior art have relatively mediocre imaging quality due to large astigmatism.

[0005] According to one aspect of an embodiment of the present application, a far-infrared optical system is disclosed, which includes, in sequence from the object side to the image side along the optical axis: a spherical lens, a super lens and an aspherical lens; the spherical lens has positive optical power, the radius of curvature of the surface of the spherical lens close to the object side is positive, and the radius of curvature of the surface of the spherical lens close to the image side is positive; the super lens has positive optical power; the aspherical lens has positive optical power, the surface of the aspherical lens close to the object side is convex to the image side, the surface of the aspherical lens close to the image side is convex to the image side, the refractive index of the aspherical lens is equal to the refractive index of the spherical lens, and the Abbe number of the aspherical lens is equal to the Abbe number of the spherical lens.

[0006] In some embodiments, the far-infrared optical system satisfies: Wherein, fno is the aperture number of the far-infrared optical system, D is the effective diameter of the surface of the spherical lens close to the object side, TTL is the total optical length of the far-infrared optical system, and R 11 is the radius of curvature of the surface of the spherical lens close to the object side, and the R 12 is the radius of curvature of the surface of the spherical lens close to the image side, and the R 31 is the radius of curvature of the surface of the aspheric lens close to the object side, and the R 32is the radius of curvature of the surface of the aspheric lens close to the image side.

[0007] In some embodiments, the far-infrared optical system satisfies: 0.45<SAG 31 / SAG 32 <0.55, wherein the intersection of the surface of the aspheric lens close to the object side and the optical axis is the first point, and the SAG 31 is the distance between the first point and the vertex of the effective radius of the surface of the aspheric lens close to the object side on the optical axis, the intersection of the surface of the aspheric lens close to the image side and the optical axis is the second point, and the SAG 32 is the distance between the second point and the vertex of the effective radius of the surface of the aspheric lens close to the image side on the optical axis.

[0008] In some embodiments, the far-infrared optical system satisfies: 0.03<(f1-f3) / f2<0.06, wherein f1 is the focal length of the spherical lens, f2 is the focal length of the super lens, and f3 is the focal length of the aspherical lens.

[0009] In some embodiments, the far-infrared optical system satisfies: 4.1 mm < f × CT1 / R 11 <4.9mm, wherein f is the effective focal length of the far-infrared optical system, CT1 is the center thickness of the spherical lens, and R 11 is the radius of curvature of the surface of the spherical lens close to the object side.

[0010] In some embodiments, the far-infrared optical system satisfies: 0.40<BFL / f<0.48, wherein the BFL is the distance between the center of the surface of the aspheric lens close to the image side and the image plane of the far-infrared optical system, and f is the effective focal length of the far-infrared optical system.

[0011] In some embodiments, the far-infrared optical system satisfies: 0.95<(CT 12 -ET 12 ) / (CT 23 -ET 23 )<1.05, wherein the CT 12 is the distance between the surface of the spherical lens close to the image side and the surface of the super lens close to the object side on the optical axis, and the ET 12 is the distance between the edge of the surface of the spherical lens close to the image side and the edge of the surface of the super lens close to the object side along the direction parallel to the optical axis; the CT 23 is the distance between the surface of the super lens close to the image side and the surface of the aspheric lens close to the object side on the optical axis, and the ET23 is the distance between the edge of the surface of the super lens close to the image side and the edge of the surface of the aspheric lens close to the object side along the direction parallel to the optical axis.

[0012] In some embodiments, the far-infrared optical system satisfies: 1.05<D / EPD<1.25, wherein D is the effective diameter of the surface of the spherical lens close to the object side, and the EPD is the entrance pupil diameter of the far-infrared optical system.

[0013] In some embodiments, the metalens satisfies the conditional formula in units of 2π radians per millimeter: The R M is the effective radius of the superlens, is the maximum phase difference of the metalens within the effective radius.

[0014] In some embodiments, the far-infrared optical system satisfies: 0.6<(ET1+ET2+ET3) / (CT1+CT2+CT3)<0.8, wherein the ET1 is the edge thickness of the spherical lens, the ET2 is the edge thickness of the superlens, the ET3 is the edge thickness of the aspheric lens, the CT1 is the center thickness of the spherical lens, the CT2 is the center thickness of the superlens, and the CT3 is the center thickness of the aspheric lens.

[0015] In some embodiments, the far-infrared optical system satisfies: 1.7<CT 12 / CT 23 <2.5, wherein the CT 12 is the distance between the surface of the spherical lens close to the image side and the surface of the super lens close to the object side on the optical axis, and the CT 23 is the distance between the surface of the super lens close to the image side and the surface of the aspheric lens close to the object side on the optical axis.

[0016] In some embodiments, the far-infrared optical system satisfies: 0.270<BFL / TTL<0.285, wherein the BFL is the distance between the center of the surface of the aspheric lens close to the image side and the image plane of the far-infrared optical system, and the TTL is the total optical length of the far-infrared optical system.

[0017] In some embodiments, the far-infrared optical system satisfies:

[0018] 1.40<f1 / f<1.50;

[0019] 9.5<f2 / f<14.5;

[0020] 0.9<f3 / f<0.95;

[0021] Among them, f1 is the focal length of the spherical lens, f2 is the focal length of the super lens, f3 is the focal length of the aspherical lens, and f is the effective focal length of the far-infrared optical system.

[0022] In some embodiments, the far-infrared optical system further includes an aperture stop disposed between the spherical lens and the super lens.

[0023] A second aspect of an embodiment of the present application provides a far-infrared optical lens, comprising: an imaging detector and any of the far-infrared optical systems described above; the imaging detector is arranged on the image plane of the far-infrared optical system.

[0024] In some embodiments, the far-infrared optical lens further comprises a lens barrel, the lens is provided with a mounting through hole, the mounting through hole comprises a first hole segment, a second hole segment, a third hole segment and a fourth hole segment which are sequentially connected along the optical axis from the object side to the image side, the diameter of the first hole segment is greater than the diameter of the second hole segment, the diameter of the second hole segment is greater than the diameter of the third hole segment, and the diameter of the third hole segment is greater than the diameter of the fourth hole segment;

[0025] The spherical lens is accommodated in the first hole segment; the aspherical lens is accommodated in the third hole segment.

[0026] In some embodiments, the far-infrared optical lens further includes a pressure ring, a first spacer ring, and a second spacer ring.

[0027] The pressing ring is connected to the lens barrel, and the pressing ring abuts against the surface of the spherical lens close to the object side;

[0028] The first spacer is accommodated in the first hole section, and the first spacer is located on the side of the spherical lens close to the super lens; the second spacer is accommodated in the second hole section, and the second spacer is respectively abutted against the first spacer and the aspherical lens; the super lens is arranged between the first spacer and the second spacer.

[0029] In some embodiments, the first spacer is provided with a fixed through hole, the fixed through hole includes a fifth hole segment and a sixth hole segment which are interconnected, the diameter of the sixth hole segment is larger than the diameter of the fifth hole segment, the superlens is accommodated in the sixth hole segment, the surface of the superlens close to the object side abuts against the first spacer, and the surface of the superlens close to the image side abuts against the second spacer.

[0030] The far-infrared optical system provided by the present application includes: a spherical lens, a super lens and an aspherical lens in sequence from the object side to the image side along the optical axis; the spherical lens has a positive focal power, the curvature radius of the surface of the spherical lens close to the object side is a positive value, and the curvature radius of the surface of the spherical lens close to the image side is a positive value; the super lens has a positive focal power; the aspherical lens has a positive focal power, the surface of the aspherical lens close to the object side is convex to the image side, the surface of the aspherical lens close to the image side is convex to the image side, the refractive index of the aspherical lens is equal to the refractive index of the spherical lens, and the Abbe number of the aspherical lens is equal to the Abbe number of the spherical lens. The far-infrared optical system provided by the present application has small astigmatism and excellent imaging quality. At the same time, the far-infrared optical system provided by the present application also has the advantages of small size and low cost. In addition, the far-infrared optical system provided by the present application has a good athermal effect in an environment of -40℃ to 80℃, so that the far-infrared optical system has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] 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.

[0032] Figure 1 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Figure 5 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0037] Figure 6 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0038] Figure 7 A relative illumination diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0039] Figure 8 A vertical axis chromatic aberration diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0040] Fig. 9 A point diagram of a far-infrared optical system in one embodiment of the present application is shown.

[0041] Fig.10 The phase distribution diagram of the superlens in the far-infrared optical system in one embodiment of the present application is shown.

[0042] Fig.11 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0043] Fig.12 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0044] Fig.13 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0045] Fig.14 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0046] Fig.15 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0047] Fig.16 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0048] Fig.17 A relative illumination diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0049] Fig.18 A vertical axis chromatic aberration diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0050] Fig.19 A point diagram of a far-infrared optical system in one embodiment of the present application is shown.

[0051] Fig. 20 The phase distribution diagram of the superlens in the far-infrared optical system in one embodiment of the present application is shown.

[0052] Fig.21 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0053] Fig. 22 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0054] Fig.23 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0055] Fig.24The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0056] Fig.25 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0057] Fig.26 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0058] Fig. 27 A relative illumination diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0059] Fig.28 A vertical axis chromatic aberration diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0060] Fig.29 A point diagram of a far-infrared optical system in one embodiment of the present application is shown.

[0061] Fig.30 The phase distribution diagram of the superlens in the far-infrared optical system in one embodiment of the present application is shown.

[0062] Fig.31 A structural cross-sectional view of a far-infrared optical lens in an embodiment of the present application is shown.

[0063] Fig.32 A structural cross-sectional view of a first spacer ring in an embodiment of the present application is shown.

[0064] Reference numerals

[0065] 100. Far infrared optical system;

[0066] 1. Spherical lens;

[0067] 2. Super lens; 21. Micro-nano structure;

[0068] 3. Aspheric lens;

[0069] 4. Aperture;

[0070] A, object plane; B, image plane; S, optical axis;

[0071] 200, lens barrel; 2001, mounting through hole; 2001a, first hole section; 2001b, second hole section; 2001c, third hole section; 2001d, fourth hole section;

[0072] 300, press circle;

[0073] 400, first spacer;

[0074] 500, second spacer ring; 5001, pressing ring body; 5001a, fixing through hole; 5001a1, fifth hole segment; 5001a2, sixth hole segment; 5002, abutting portion.

[0075] 1000. Far infrared optical lens. DETAILED DESCRIPTION

[0076] 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.

[0077] 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 unclear.

[0078] The present application provides a far-infrared optical system. The prior art that is closest to the specifications to be achieved by the present application is Chinese patent CN117471664A. Chinese patent CN117471664A discloses an infrared optical system and an infrared optical lens. The effective focal length of the infrared optical lens is close to the effective focal length of the infrared optical system provided by the present application. However, the sagittal curve and the meridional curve in the MTF curve diagram of the lens are relatively scattered, which shows that the lens has a large astigmatism, which will cause the focal planes of the center and the edge of the lens to be in different positions, resulting in poor edge image quality of the lens. Therefore, the image quality of the lens needs to be improved.

[0079] 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 S is the center line of the light beam. Figure 1In the far-infrared optical system 100, the left side of the leftmost lens is the object side, and the object plane A is located on the object side. The right side of the rightmost lens is the image side, 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 consistent with the direction from the object side to the image side along the optical axis S, that is, the direction from the object side to the image side along the optical axis S is equivalent to the direction from the object plane A to the image plane B along the optical axis S. The far-infrared optical system 100 includes, in order from the object plane A to the image plane B along the optical axis S: a spherical lens 1, a super lens 2, and an aspherical lens 3.

[0080] The spherical lens 1 has positive refractive power, the curvature radius of the surface of the spherical lens 1 close to the object surface A is a positive value, and the curvature radius of the surface of the spherical lens 1 close to the image surface B is a positive value.

[0081] The superlens 2 has a positive optical power, and is used to modulate the phase of the incident light to correct the dispersion of a wide spectrum. The superlens 2 provides different focal lengths in different wavelengths. The superlens 2 cooperates with other lenses to converge the focal points of different single wavelength light image planes at the same position to achieve the achromatic function. The superlens 2 is produced by semiconductor technology, and its single chip cost is low when mass-produced, which can reduce the production cost of the far-infrared optical system 100, so that the far-infrared optical system 100 provided by the present application has the advantage of relatively low cost.

[0082] The superlens 2 includes a substrate and a superstructure unit located on the surface of the substrate, and a micro-nano structure 21 is provided at the vertex and / or center of the superstructure unit. The filling material between the micro-nano structures 21 is air or other materials that are transparent in the working band. The micro-nano structure 21 can be provided on the surface of the substrate facing the object plane A, or on the surface of the substrate facing the image plane B, or both the surface of the substrate facing the object plane A and the surface of the substrate facing the image plane B are provided with a micro-nano structure 21. The micro-nano structure 21 can be provided with one layer, two layers or more than three layers. According to the phase modulation method adopted, the various parameters of the micro-nano structure 21 can be adaptively configured using a matching phase modulation formula, so that the superlens 2 can achieve corresponding optical performance.

[0083] It should be noted that although the micro-nano structures 21 in the drawings of the present application are all located on the side of the substrate facing the spherical lens 1, the micro-nano structures 21 are all located on the side of the substrate away from the spherical lens 1, and the micro-nano structures 21 are also arranged on both sides of the substrate within the protection scope of the present application.

[0084] The aspheric lens 3 has positive power, the surface of the aspheric lens 3 close to the object surface A is convex to the image surface B, and the surface of the aspheric lens 3 close to the image surface B is convex to the image surface B. The refractive index of the aspheric lens 3 is equal to the refractive index of the spherical lens 1, and the Abbe number of the aspheric lens 3 is equal to the Abbe number of the spherical lens 1.

[0085] The far-infrared optical system provided by the present application has small astigmatism and excellent imaging quality. At the same time, the far-infrared optical system 100 provided by the present application also has the advantages of small size and low cost. Moreover, the far-infrared optical system 100 provided by the present application has a good athermal effect in an environment of -40°C to 80°C, so that the far-infrared optical system 100 has a wide range of applications.

[0086] In some embodiments, the material of the aspheric lens 3 is the same as that of the spherical lens 1 , so that the refractive index of the aspheric lens 3 is equal to that of the spherical lens 1 , and the Abbe number of the aspheric lens 3 is equal to that of the spherical lens 1 .

[0087] In some embodiments, the far-infrared optical system 100 satisfies Condition 1:

[0088]

[0089] Wherein, fno is the aperture number of the far-infrared optical system 100, and the aperture number is the ratio of the focal length of the far-infrared optical system 100 to the entrance pupil diameter. D is the effective diameter of the surface of the spherical lens 1 close to the object plane A. The effective diameter is also called the net aperture. The effective diameter is the maximum light beam diameter that the lens can pass through. The effective diameter is usually used to indicate the ability of a lens or optical system to collect light. In the present application, D is the maximum aperture corresponding to when light passes through the spherical lens 1, and the unit of D is the unit of length. TTL (Total Track Length, abbreviated as TTL, total optical length) is the total optical length of the far-infrared optical system 100. In the present application, TTL is the distance between the center of the surface of the spherical lens 1 close to the object plane A and the image plane B of the far-infrared optical system 100 on the optical axis S, and the unit of TTL is the unit of length. R 11 R is the radius of curvature of the surface of the spherical lens 1 close to the object surface A, and its unit is length unit. 12 R is the radius of curvature of the surface of the spherical lens 1 close to the image surface B, and its unit is the unit of length. 31 R is the radius of curvature of the surface of the aspheric lens 3 close to the object surface A, and its unit is length unit. 32 is the radius of curvature of the surface of the aspheric lens 3 close to the image plane B, and its unit is the unit of length. D, TTL, R 11 , R 12 , R 31 and R 32 have the same dimension, for example, millimeters.

[0090] Conditional formula 1 ensures that the far-infrared optical system 100 can reduce the volume while satisfying the requirements of large aperture and high light input, while also obtaining good imaging quality.

[0091] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 2:

[0092] 0.45<SAG 31 / SAG 32 <0.55

[0093] The intersection of the surface of the aspheric lens 3 close to the object plane A and the optical axis S is the first point, SAG 31 It is the distance between the first point and the vertex of the effective radius of the surface of the aspheric lens 3 close to the object surface A on the optical axis S, where the “distance on the optical axis S” is equal to the length of the orthographic projection of the straight-line distance between the first point and the vertex of the effective radius of the surface of the aspheric lens 3 close to the object surface A on the optical axis S. SAG 31 The unit is the length unit. The intersection of the surface of the aspheric lens 3 close to the image plane B and the optical axis S is the second point, SAG 32 It is the distance between the second point and the vertex of the effective radius of the surface of the aspheric lens 3 close to the image surface B on the optical axis S, where “the distance on the optical axis S” is equal to the length of the orthographic projection of the straight-line distance between the second point and the vertex of the effective radius of the surface of the aspheric lens 3 close to the image surface B on the optical axis S. SAG 32 The unit is the length unit. SAG 31 and SAG 32 have the same dimension, for example, millimeters.

[0094] When the far-infrared optical system 100 satisfies conditional formula 2, the thickness ratio of the aspheric lens 3 (the ratio of the thickness at the thickest point to the thickness at the thinnest point) can be indirectly controlled, and the degree of deflection of light when it enters and exits the aspheric lens 3 can be constrained, which is beneficial to improving the uniformity of light on the image plane B and increasing the relative illumination.

[0095] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 3:

[0096] 0.03<(f1-f3) / f2<0.06

[0097] Wherein, f1 is the focal length of the spherical lens 1, and its unit is the length unit. f2 is the focal length of the metalens 2, and its unit is the length unit. f3 is the focal length of the aspherical lens 3, and its unit is the length unit. The dimensions of f1, f2, and f3 are the same, for example, all are millimeters.

[0098] The far-infrared optical system 100 satisfies conditional equation 3, and can effectively constrain the optical power distribution among the spherical lens 1, the metalens 2, and the aspherical lens 3, thereby reducing the on-axis aberration and the off-axis aberration and the resulting chromatic aberration, which helps to improve the imaging quality.

[0099] In some embodiments, the far-infrared optical system 100 satisfies Condition 4:

[0100] 4.1mm<f×CT1 / R 11 <4.9mm

[0101] Wherein, f is the effective focal length of the far-infrared optical system 100, and its unit is the length unit. CT1 is the center thickness of the spherical lens 1, that is, CT1 is the thickness of the spherical lens 1 on the optical axis S, and its unit is the length unit. 11 is the radius of curvature of the surface of the spherical lens 1 close to the object surface A, and its unit is the unit of length. f, CT1 and R 11 have the same dimension, for example, millimeters.

[0102] The far-infrared optical system 100 satisfies conditional formula 4, which can effectively control the volume and surface shape of the spherical lens 1 as the first lens and the weight distribution of the far-infrared optical system 100, thereby avoiding the problem of uneven focal power caused by the excessive volume of the spherical lens 1. In addition, the far-infrared optical system 100 satisfies conditional formula 4, which can also reduce the sensitivity of the far-infrared optical system 100 to tolerances, and improve the assembly yield of the lens corresponding to the far-infrared optical system 100.

[0103] In some embodiments, the far-infrared optical system 100 satisfies Condition 5:

[0104] 0.40<BFL / f<0.48

[0105] Among them, BFL (Back Focal Length, abbreviated as BFL) is the back focal length of the far-infrared optical system 100. In the present application, BFL is equal to the distance between the center of the surface of the aspherical lens 3 close to the image plane B and the image plane B of the far-infrared optical system 100, and the unit of BFL is the length unit. f is the effective focal length of the far-infrared optical system 100, and its unit is the length unit. BFL and f have the same dimension, for example, both are millimeters. The far-infrared optical system 100 satisfies conditional formula 5, which ensures the rationality of the value of the back focal length.

[0106] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 6:

[0107] 0.95<(CT 12 -ET 12 ) / (CT 23 -ET 23 )<1.05

[0108] Among them, CT 12 is the distance between the surface of spherical lens 1 close to image plane B and the surface of superlens 2 close to object plane A on the optical axis S, CT 12 The unit of ET is the length unit. 12 is the distance between the edge of the surface of the spherical lens 1 close to the image plane B and the edge of the surface of the superlens 2 close to the object plane A along the direction parallel to the optical axis S, ET 12 The unit of CT is the length unit.23 is the distance between the surface of the super lens 2 close to the image plane B and the surface of the aspheric lens 3 close to the object plane A on the optical axis S, CT 23 The unit of ET is the length unit. 23 is the distance between the edge of the surface of the super lens 2 close to the image plane B and the edge of the surface of the aspheric lens 3 close to the object plane A along the direction parallel to the optical axis S, ET 23 The unit of CT is the length unit. 12 , E.T. 12 , CT 23 and E.T. 23 have the same dimension, for example, millimeters.

[0109] Satisfying conditional formula 6 can make the total optical length of the far-infrared optical system 100 relatively short. At the same time, the distance between the lenses can be controlled to avoid collisions between the lenses due to the short distance, which makes it difficult to assemble the lenses corresponding to the far-infrared optical system 100, thus ensuring that the lenses corresponding to the far-infrared optical system 100 can be assembled smoothly.

[0110] In some embodiments, the far-infrared optical system 100 satisfies conditional equation 7:

[0111] 1.05<D / EPD<1.25

[0112] Wherein, D is the effective diameter of the surface of the spherical lens 1 close to the object surface A, and its unit is a length unit. Please refer to the above for the definition of the effective diameter, and this article will not elaborate on its definition. In this application, D is the maximum aperture corresponding to when the light passes through the spherical lens 1, and its unit is a length unit. EPD is the entrance pupil diameter of the far-infrared optical system 100, and its unit is a length unit. D and EPD have the same dimension, for example, both are millimeters.

[0113] When the conditional expression 7 is satisfied, the far-infrared optical system 100 can have a large aperture and a small volume.

[0114] In some embodiments, the metalens 2 satisfies the conditional equation 8 with 2π radians per millimeter as a unit:

[0115]

[0116] The unit of conditional expression 8 is 2πrad / mm, taking the upper limit 1.2 as an example. M is the effective radius of the superlens 2, in millimeters. is the maximum phase difference of the superlens 2 within the effective radius, and its unit is 2πrad.

[0117] The super lens 2 satisfies conditional expression 8, so that the far-infrared optical system 100 can have a large aperture and a small volume.

[0118] In some embodiments, the far-infrared optical system 100 satisfies Condition 9:

[0119] 0.6<(ET1+ET2+ET3) / (CT1+CT2+CT3)<0.8

[0120] Wherein, ET1 is the edge thickness of spherical lens 1, and its unit is length unit. CT1 is the center thickness of spherical lens 1, and its unit is length unit. ET2 is the edge thickness of metalens 2, and its unit is length unit. CT2 is the center thickness of metalens 2, and its unit is length unit. ET3 is the edge thickness of aspheric lens 3, and its unit is length unit. CT3 is the center thickness of aspheric lens 3, and its unit is length unit.

[0121] The super lens 2 satisfies conditional expression 9, so that the far-infrared optical system 100 can have a large aperture and a small volume.

[0122] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 10:

[0123] 1.7<CT 12 / CT 23 <2.5

[0124] Among them, CT 12 It is the distance between the surface of spherical lens 1 close to image plane B and the surface of super lens 2 close to object plane A on the optical axis S, and its unit is length unit. 23 It is the distance between the surface of the super lens 2 close to the image plane B and the surface of the aspheric lens 3 close to the object plane A on the optical axis S, and its unit is the length unit. 12 and CT 23 The dimensions of are the same, for example, both are millimeters. When the conditional expression 10 is satisfied, the far-infrared optical system 100 can have a large aperture and a small volume at the same time.

[0125] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 11:

[0126] 0.270<BFL / TTL<0.285

[0127] BFL is the distance between the center of the surface of the aspherical lens 3 close to the image plane B and the image plane B of the far-infrared optical system 100, and its unit is a length unit. TTL is the total optical length of the far-infrared optical system 100, and its unit is a length unit.

[0128] Conditional expression 11 ensures the back focal length of the far-infrared optical system 100 while limiting the total optical length, so that the far-infrared optical system 100 has the advantages of being small and light.

[0129] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 12:

[0130] 1.40<f1 / f<1.50

[0131] Wherein, f1 is the focal length of the spherical lens 1 at the central wavelength, and its unit is a length unit. f is the effective focal length of the far-infrared optical system 100, and its unit is a length unit. f1 and f have the same dimension, for example, both are millimeters.

[0132] Conditional expression 12 effectively controls the proportion of the optical power of the spherical lens 1 in the far-infrared optical system 100. By reasonably allocating the optical power proportion of the spherical lens 1, the on-axis aberration and the off-axis aberration are effectively controlled, and the imaging quality can be improved.

[0133] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 13:

[0134] 9.5<f2 / f<14.5

[0135] Wherein, f2 is the focal length of the metalens 2 at the central wavelength, and its unit is a length unit. f is the effective focal length of the far-infrared optical system 100, and its unit is a length unit. f2 and f have the same dimension, for example, both are millimeters.

[0136] Conditional expression 13 effectively controls the proportion of the optical power of the metalens 2 in the far-infrared optical system 100. By reasonably allocating the proportion of the optical power of the metalens 2, the dispersion of the far-infrared optical system 100 can be effectively controlled.

[0137] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 14:

[0138] 0.9<f3 / f<0.95

[0139] Wherein, f3 is the focal length of the aspheric lens 3 at the central wavelength, and its unit is a length unit. f is the effective focal length of the far-infrared optical system 100, and its unit is a length unit. f3 and f have the same dimension, for example, both are millimeters.

[0140] Conditional formula 14 effectively controls the proportion of the optical power of the aspherical lens 3 in the far-infrared optical system 100. By reasonably allocating the proportion of the optical power of the aspherical lens 3, the axial chromatic aberration and the off-axial chromatic aberration can be effectively controlled to improve the imaging quality. At the same time, conditional formula 14 also ensures that the back focal length is large enough. The increase in the back focal length can reduce the mechanical volume of the corresponding lens while ensuring the optical power of the far-infrared optical system 100.

[0141] In some embodiments, the far-infrared optical system 100 also includes an aperture 4, which is disposed between the spherical lens 1 and the metalens 2. The aperture 4 is used to limit the amount of light entering the far-infrared optical system 100 to ensure that the far-infrared optical system 100 can work effectively and generate high-quality images.

[0142] In some embodiments, the far-infrared optical system 100 further includes a protective member (not shown) for protecting each lens. The protective member can transmit light, and is located on the side of the aspheric lens 3 away from the super lens 2 along the optical axis S, that is, the far-infrared optical system 100 along the optical axis S from the object plane A to the image plane B is composed of the spherical lens 1, the super lens 2, the aspheric lens 3 and the protective member.

[0143] The protective member may be in the form of protective glass, and may be made of silicon or germanium.

[0144] The working wavelength of the far-infrared optical system 100 is 8 microns to 12 microns. The target requirements of the far-infrared optical system 100 for various system parameters are shown in Table 1.

[0145] Table 1. Target requirements for various system parameters of far-infrared optical system 100

[0146] Optical indicators Required value Effective focal length 10mm fno 0.9 Resolution 256×192 Pixel size 12μm Lens field of view 17.5°×13.2° No thermalization required -40℃～80℃ distortion ≤2％ Relative Illuminance ＞90％ TTL ≤16.2mm BFL ≥4mm

[0147] As can be seen from Table 1, the effective focal length of the far-infrared optical system 100 needs to be 10 mm, and the value of fno needs to be less than or equal to 0.9. The minimum requirement for the field of view angle of the far-infrared optical system 100 is 17.5°×13.2°. The lens corresponding to the far-infrared optical system 100 needs to meet the athermal requirement at least at -40°C to 80°C. For example, the lens corresponding to the far-infrared optical system 100 can also meet the athermal requirement within the temperature range of -50°C to 80°C. The maximum distortion of the far-infrared optical system 100 is 2%. The relative illumination of the far-infrared optical system 100 needs to be greater than 90%, the total optical length of the far-infrared optical system 100 needs to be less than or equal to 16.2 mm, and the back focal length of the far-infrared optical system 100 needs to be at least 4 mm. The resolution of the image sensor adapted to the far-infrared optical system 100 is 256×192, and the pixel size of the image sensor is 12 microns. It should be noted that the specifications of the image sensor adapted by the far-infrared optical system 100 are not limited to image sensors with a resolution of 256×192 and a pixel size of 12 microns.

[0148] The present application exemplarily provides three far-infrared optical systems 100 that meet usage requirements in three embodiments. Next, the far-infrared optical systems 100 provided by the various embodiments of the present application are introduced in detail.

[0149] Example 1

[0150] Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 1. Figure 1 The mid-infrared optical system 100 includes, in order from the object plane A to the image plane B along the optical axis S: a spherical lens 1, an aperture 4, a super lens 2, and an aspherical lens 3. The effective focal length of the far-infrared optical system 100 provided in Example 1 is 10 mm. Starting from the object plane A, along the optical axis S from the object plane A to the image plane B, the surfaces in the far-infrared optical system 100 are numbered, and the parameters of the surfaces are summarized to obtain the following Table 2.

[0151] Table 2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 1

[0152] Surface number Optical Components Surface type Radius of curvature thickness Material 0 flat unlimited unlimited 1 Spherical lens Spherical 9.480mm 4.596mm Chalcogenide glass 2 Spherical 10.401mm 1.621mm 3 Aperture flat unlimited 0.578mm 4 Super Lens flat unlimited 0.300mm silicon 5 flat unlimited 1.200mm 6 Aspheric Lenses even aspherical surface -10.333mm 3.338mm Chalcogenide glass 7 even aspherical surface -7.635mm 4.402mm 8 flat unlimited

[0153] For each surface in Table 2, surface 0 is the object plane A. Surface 1 is the surface of the spherical lens 1 close to the object plane A, and surface 2 is the surface of the spherical lens 1 close to the image plane B. Surface 3 is the aperture 4. Surface 4 is the surface of the super lens 2 close to the object plane A, and surface 5 is the surface of the super lens 2 close to the image plane B. Surface 6 is the surface of the aspherical lens 3 close to the object plane A, and surface 7 is the surface of the aspherical lens 3 close to the image plane B. Surface 8 is the image plane B.

[0154] As can be seen from Table 2, the radius of curvature of surface 0 is infinite, that is, surface 0 is a plane, the distance between surface 0 and surface 1 is uncertain, and the material between surface 0 and surface 1 is air. Surface 1 is a spherical surface, the radius of curvature of surface 1 is 9.480 mm, the distance between surface 1 and surface 2 is 4.596 mm, and the material between surface 1 and surface 2 is chalcogenide glass. Surface 2 is a spherical surface, the radius of curvature of surface 2 is 10.401 mm, the distance between surface 2 and surface 3 is 1.621 mm, and 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, and the distance between surface 3 and surface 4 is 0.578 mm. 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, the distance between surface 5 and surface 6 is 1.200 mm, and the material between surface 4 and surface 5 is air. Surface 6 is an aspherical surface, the radius of curvature of surface 6 is -10.333 mm, the distance between surface 6 and surface 7 is 3.338 mm, and the material between surface 6 and surface 7 is chalcogenide glass. Surface 7 is an aspherical surface, the radius of curvature of surface 7 is -7.635 mm, the distance between surface 7 and surface 8 is 4.402 mm, and the material between surface 7 and surface 8 is air.

[0155] Surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0156]

[0157] 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 S direction; 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, etc. of surface 6 and surface 7 can be obtained from Table 3.

[0158] Table 3 Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 1

[0159] surface k A B C D 6 -5.8979 -0.07549 -8.024823e-6 7.230433e-7 1.497530e-8 7 -0.4684 -6.478574e-4 1.093568e-5 -5.239033e-7 -4.271423e-8

[0160] Refer to Table 3, for surface 6, K is -5.8979, A is -0.07549, B is -8.024823e-6, C is 7.230433e-7, and D is 1.497530e-8. For surface 7, K is -0.4684, A is -6.478574e-4, B is 1.093568e-5, C is -5.239033e-7, and D is -4.271423e-8.

[0161] See also Figure 2 , Figure 2 The MTF field curve of the far-infrared optical system 100 provided in Example 1 at 20° C. is shown. MTF, also known as modulation transfer function, is an important indicator for describing the imaging quality of an optical system. The larger the MTF value, the better the imaging quality. Figure 2 The sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Figure 2 The horizontal axis in is the field of view angle, and its unit is degree. Figure 2 The vertical axis in is the MTF value. Figure 2 It can be seen that within the entire field of view, at a spatial frequency of 42 lp / mm, the MTF is greater than 0.4, which is close to the diffraction limit. Therefore, the far-infrared optical system 100 provided in Example 1 has excellent imaging quality. Figure 2The differences between the sagittal curve S1 and the meridional curve T1, the sagittal curve S2 and the meridional curve T2, and the sagittal curve S3 and the meridional curve T3 are small, which shows that the astigmatism of the far-infrared optical system 100 is small. In addition, the sagittal curves S1, S2, and S3 decrease slowly at the edge, which shows that the edge image quality of the far-infrared optical system 100 is also excellent.

[0162] 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 sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Figure 3 The horizontal axis in is the field of view angle, and its unit is degree. Figure 3 The vertical axis in is the MTF value. Figure 3 It can be seen that within the 0.9 field of view (10.44°), at a spatial frequency of 42lp / mm, the MTF is greater than 0.3.

[0163] 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 sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Figure 4 The horizontal axis in is the field of view angle, and its unit is degree. Figure 4 The vertical axis in is the MTF value. Figure 4 It can be seen that within the 0.9 field of view (10.44°), at a spatial frequency of 42lp / mm, the MTF is greater than 0.3.

[0164] comprehensive Figures 2 to 4 It can be seen that in a working environment of -40℃~80℃, the MTF of the far-infrared optical system 100 at a spatial frequency of 42lp / mm within a 0.9 field of view is greater than 0.3, indicating that the far-infrared optical system 100 has a good athermal effect and can meet the working environment with complex and changeable temperature.

[0165] See also Figure 5 , Figure 5The field curvature diagram of the far-infrared optical system 100 provided in Example 1 under infrared light with wavelengths of 8 microns, 10 microns and 12 microns is shown, wherein T1, T2 and T3 are the field curvatures of the infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the meridional direction, respectively, and S1, S2 and S3 are the field curvatures of the infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the sagittal direction, respectively. Figure 5 The horizontal axis is field curvature, and its unit is millimeter. Figure 5 The vertical axis is the field of view angle, and its unit is degree. Figure 5 It can be seen that the meridional field curvature is 0.0195 mm and the sagittal field curvature is 0.0358 mm in the full field of view, which meets the requirements for field curvature in the excellent imaging quality standard.

[0166] See also Figure 6 , Figure 6 The distortion diagram of the far-infrared optical system 100 provided in Example 1 under infrared light with wavelengths of 8 microns, 10 microns and 12 microns is shown. Figure 6 The intervals between the three curves in are too small, so that the three curves almost overlap, and therefore, the three curves are not distinguished. Figure 6 The horizontal axis is the percentage of distortion. Figure 6 The vertical axis is the field of view angle, in degrees. Figure 6 It can be seen that the maximum distortion is 1.07%, which meets the requirements and also meets the distortion requirements of the excellent imaging quality standard.

[0167] See also Figure 7 , Figure 7 1 shows a relative illumination diagram of the far-infrared optical system 100 provided in Example 1, Figure 7 The horizontal axis in is the field of view angle, and its unit is degree. Figure 7 The vertical axis in is the relative illumination value. Figure 7 It can be seen that within the entire field of view, the relative illumination is greater than or equal to 90%. Therefore, the brightness of the image plane B is relatively uniform, meeting the requirement for relative illumination in the excellent imaging quality standard.

[0168] See also Figure 8 , Figure 8 FIG. 1 shows a vertical axis chromatic aberration diagram of the far-infrared optical system 100 provided in Example 1, wherein: Figure 8 The deviation degree of light with a wavelength of 8 microns and a wavelength of 12 microns in the direction perpendicular to the optical axis S is demonstrated based on the position of light with a wavelength of 10 microns on the vertical axis image plane, where the "vertical axis image plane" refers to image plane B. Figure 8 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane, in microns. Figure 8 The vertical axis is the field of view angle, and its unit is degree. Figure 8The M1 curve in the figure corresponds to light with a wavelength of 8 microns. Figure 8 The M2 curve in corresponds to light with a wavelength of 10 microns. Figure 8 The M3 curve in corresponds to light with a wavelength of 12 microns. Figure 8 It can be seen that within the full field of view, the maximum vertical chromatic aberration is about 4.82 microns, which is less than half a pixel. The chromatic aberration is small and the dispersion is not obvious, which meets the chromatic aberration requirements of excellent imaging quality standards.

[0169] See also Fig. 9 , Fig. 9 The point diagram of the far-infrared optical system 100 provided in Example 1 is shown. Fig. 9 It can be seen that within the 0.94 field of view (10.9°), the spot diagrams are all smaller than one pixel. Therefore, it can be concluded that within the 0.9 field of view (10.11°), the spot diagrams are all smaller than one pixel, and the light convergence is more concentrated.

[0170] See also Fig.10 , Fig.10 : shows a phase curve diagram of the metalens 2 of the far-infrared optical system 100 provided in Example 1, Fig.10 The abscissa of is the radius of the superlens 2, and its unit is millimeter. Fig.10 The ordinate is the phase of the superlens 2, and its unit is 2πrad. Fig.10 It can be seen that the maximum phase difference of the superlens 2 is less than 3.21×2πrad.

[0171] Example 2

[0172] Fig.11 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 2. Fig.11 The mid-infrared optical system 100 includes, in order from the object plane A to the image plane B along the optical axis S: a spherical lens 1, an aperture 4, a super lens 2, and an aspherical lens 3. The effective focal length of the far-infrared optical system 100 provided in Example 2 is 10 mm. Starting from the object plane A, along the optical axis S from the object plane A to the image plane B, the surfaces in the far-infrared optical system 100 are numbered, and the parameters of the surfaces are summarized to obtain the following Table 4.

[0173] Table 4. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 2

[0174] Surface number Optical Components Surface type Radius of curvature thickness Material 0 flat unlimited unlimited 1 Spherical lens Spherical 9.617mm 4.000mm Chalcogenide glass 2 Spherical 11.210mm 2.791mm 3 Aperture flat unlimited 0.160mm 4 Super Lens flat unlimited 0.300mm silicon 5 flat unlimited 1.208mm 6 Aspheric Lenses even aspherical surface -8.685mm 2.968mm Chalcogenide glass 7 even aspherical surface -6.739mm 4.484mm 8 flat unlimited

[0175] For the analysis of Table 4, reference may be made to Example 1, and no further analysis is performed in this example.

[0176] Surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0177]

[0178] 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 S direction; 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, etc. of surface 6 and surface 7 can be obtained from Table 5.

[0179] Table 5. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 2

[0180] surface K A B C D 6 -5.71970 -0.00112 -7.333245e-6 5.123125e-7 -1.852356e-8 7 -0.85902 -3.548513e-4 1.255474e-5 -1.483566e-7 -2.645965e-10

[0181] For the use of Table 5, please refer to Example 1, which will not be described again in this example.

[0182] See also Fig.12 , Fig.12 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at 20° C. is shown. Fig.12 The sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Fig.12 The horizontal axis in is the field of view angle, and its unit is degree. Fig.12 The vertical axis in is the MTF value. Fig.12 It can be seen that within the full field of view, at a spatial frequency of 42lp / mm, the MTF is greater than 0.38, and within a 0.8 field of view (9.28°) at a spatial frequency of 42lp / mm, the MTF is greater than 0.48. Therefore, the far-infrared optical system 100 provided in Example 2 has excellent imaging quality. Fig.12 The differences between the sagittal curve S1 and the meridional curve T1, the sagittal curve S2 and the meridional curve T2, and the sagittal curve S3 and the meridional curve T3 are small, which shows that the astigmatism of the far-infrared optical system 100 is small. In addition, the sagittal curves S1, S2, and S3 decrease slowly at the edge, which shows that the edge image quality of the far-infrared optical system 100 is also excellent.

[0183] See also Fig.13 , Fig.13 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at -40°C is shown. Fig.13The sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Fig.13 The horizontal axis in is the field of view angle, and its unit is degree. Fig.13 The vertical axis in is the MTF value. Fig.13 It can be seen that within the full field of view, at a spatial frequency of 42lp / mm, the MTF is greater than 0.2. Within the 0.8 field of view (9.28°), the MTF at a spatial frequency of 42lp / mm is greater than 0.32.

[0184] See also Fig.14 , Fig.14 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at 80° C. is shown. Fig.14 The sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Fig.14 The horizontal axis in is the field of view angle, and its unit is degree. Fig.14 The vertical axis in is the MTF value. Fig.14 It can be seen that within the full field of view, at a spatial frequency of 42lp / mm, the MTF is greater than 0.2. Within the 0.8 field of view (9.28°), the MTF at a spatial frequency of 42lp / mm is greater than 0.32.

[0185] comprehensive Figure 12 to Figure 14 It can be seen that in a working environment of -40°C to 80°C, the MTF of the far-infrared optical system 100 at a spatial frequency of 42lp / mm within a 0.8 field of view (9.28°) is greater than 0.32, indicating that the far-infrared optical system 100 has a good athermal effect and can meet the needs of a working environment with complex and changeable temperatures.

[0186] See also Fig.15 , Fig.15 The field curvature diagram of the far-infrared optical system 100 provided in Example 2 under infrared light with wavelengths of 8 microns, 10 microns and 12 microns is shown, wherein T1, T2 and T3 are the field curvatures of the infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the meridional direction, respectively, and S1, S2 and S3 are the field curvatures of the infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the sagittal direction, respectively. Fig.15 The horizontal axis is field curvature, and its unit is millimeter. Fig.15 The vertical axis is the field of view angle, and its unit is degree. Fig.15 It can be seen that the meridian field curvature is 0.0389 mm and the sagittal field curvature is 0.0512 mm in the full field of view, which meets the requirements for field curvature in the excellent imaging quality standard.

[0187] See also Fig.16 , Fig.16 The distortion diagram of the far-infrared optical system 100 provided in Example 2 under infrared light with wavelengths of 8 microns, 10 microns and 12 microns is shown. Fig.16 The intervals between the three curves in are too small, so that the three curves almost overlap, and therefore, the three curves are not distinguished. Fig.16 The horizontal axis is the percentage of distortion. Fig.16 The vertical axis is the field of view angle, in degrees. Fig.16 It can be seen that the maximum distortion is 0.946%, which meets the requirements and also meets the distortion requirements of the excellent imaging quality standard.

[0188] See also Fig.17 , Fig.17 : shows a relative illumination diagram of the far-infrared optical system 100 provided in Example 2, Fig.17 The horizontal axis in is the field of view angle, and its unit is degree. Fig.17 The ordinate in is the relative illumination. Fig.17 It can be seen that within the entire field of view, the relative illumination is greater than or equal to 90%. Therefore, the brightness of the image plane B is relatively uniform, meeting the requirement for relative illumination in the excellent imaging quality standard.

[0189] See also Fig.18 , Fig.18 The vertical axis chromatic aberration diagram of the far-infrared optical system 100 provided in Example 2 is shown, wherein: Fig.18 The deviation degree of light with a wavelength of 8 microns and a wavelength of 12 microns in the direction perpendicular to the optical axis S is demonstrated based on the position of light with a wavelength of 10 microns on the vertical axis image plane, where the "vertical axis image plane" refers to image plane B. Fig.18 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane B, in microns. Fig.18 The vertical axis is the field of view angle, and its unit is degree. Fig.18 The M1 curve in the figure corresponds to light with a wavelength of 8 microns. Fig.18 The M2 curve in corresponds to light with a wavelength of 10 microns. Fig.18 The M3 curve in corresponds to light with a wavelength of 12 microns. Fig.18 It can be seen that within the full field of view, the maximum vertical chromatic aberration is about 4.70 microns, which is less than half a pixel. The chromatic aberration is small and the dispersion is not obvious, which meets the chromatic aberration requirements of excellent imaging quality standards.

[0190] See also Fig.19 , Fig.19 The point diagram of the far-infrared optical system 100 provided in Example 2 is shown. Fig.19 It can be seen that within the 0.8 field of view (9.28°), the spot diagrams are all smaller than one pixel, and the light convergence is relatively concentrated.

[0191] See also Fig. 20 , Fig. 20 : shows a phase curve diagram of the metalens 2 of the far-infrared optical system 100 provided in Example 2, Fig.19 The abscissa of is the radius of the superlens 2, and its unit is millimeter. Fig. 20 The ordinate is the phase of the superlens 2, and its unit is 2πrad. Fig. 20 It can be seen that the maximum phase difference of the superlens 2 is less than 3.69×2πrad.

[0192] Example 3

[0193] Fig.21 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 3. Fig.21 The mid-infrared optical system 100 includes: a spherical lens 1, an aperture 4, a super lens 2, and an aspherical lens 3 in order from the object plane A to the image plane B along the optical axis S. The effective focal length of the far-infrared optical system 100 provided in Example 3 is 10 mm. Starting from the object plane A, along the optical axis S from the object plane A to the image plane B, the surfaces in the far-infrared optical system 100 are numbered, and the parameters of each surface are summarized to obtain the following Table 6.

[0194] Table 6. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 3

[0195] Surface number Optical Components Surface type Radius of curvature thickness Material 0 flat unlimited unlimited 1 Spherical lens Spherical 9.493mm 4.582mm Chalcogenide glass 2 Spherical 10.478mm 1.648mm 3 Aperture flat unlimited 0.587mm 4 Super Lens flat unlimited 0.300mm silicon 5 flat unlimited 1.196mm 6 Aspheric Lenses even aspherical surface -10.368mm 3.333mm Chalcogenide glass 7 even aspherical surface -7.686mm 4.382mm 8 flat unlimited

[0196] For the analysis of Table 6, reference may be made to Example 1, and no further analysis is performed in this example.

[0197] Surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0198]

[0199] 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 S direction; 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, etc. of surface 6 and surface 7 can be obtained from Table 7.

[0200] Table 7. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 3

[0201] surface k A B C D 6 6.395059 -0.00140 -1.085494e-6 7.386845e-7 -3.047554e-9 7 -0.468574 -6.299928e-4 1.046439e-5 -5.695473e-7 -3.554732e-8

[0202] For the use of Table 7, please refer to Example 1, which will not be described again in this example.

[0203] See also Fig. 22 , Fig. 22 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at 20° C. is shown. Fig. 22 The sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Fig. 22 The horizontal axis in is the field of view angle, and its unit is degree. Fig. 22 The vertical axis in is the MTF value. Fig. 22 It can be seen that within the entire field of view, at a spatial frequency of 42 lp / mm, the MTF is greater than 0.4. Therefore, the far-infrared optical system 100 provided in Example 2 has excellent imaging quality. Fig. 22 The differences between the sagittal curve S1 and the meridional curve T1, the sagittal curve S2 and the meridional curve T2, and the sagittal curve S3 and the meridional curve T3 are small, which shows that the astigmatism of the far-infrared optical system 100 is small. In addition, the sagittal curves S1, S2, and S3 decrease slowly at the edge, which shows that the edge image quality of the far-infrared optical system 100 is also excellent.

[0204] See also Fig.23 , Fig.23 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at -40°C is shown. Fig.23 The sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Fig.23 The horizontal axis in is the field of view angle, and its unit is degree. Fig.23 The vertical axis in is the MTF value. Fig.23 It can be seen that within the full field of view, at a spatial frequency of 42lp / mm, the MTF is greater than 0.3.

[0205] See also Fig.24 , Fig.24 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at 80° C. is shown. Fig.24 The sagittal image curve S1 and the meridional image curve T1 of the MTF of 10lp / mm spatial frequency as it changes with the field of view, the sagittal image curve S2 and the meridional image curve T2 of the MTF of 21lp / mm spatial frequency as it changes with the field of view, and the sagittal image curve S3 and the meridional image curve T3 of the MTF of 42lp / mm spatial frequency as it changes with the field of view are listed. Fig.24 The horizontal axis in is the field of view angle, and its unit is degree. Fig.24 The vertical axis in is the MTF value. Fig.24 It can be seen that within the 0.9 field of view (10.44°), at a spatial frequency of 42lp / mm, the MTF is greater than 0.3.

[0206] comprehensive Figure 22 to Figure 24 It can be seen that in a working environment of -40°C to 80°C, the MTF of the far-infrared optical system 100 at a spatial frequency of 42lp / mm within a 0.9 field of view (10.44°) is greater than 0.3, indicating that the far-infrared optical system 100 has a good athermal effect and can meet the needs of a working environment with complex and changeable temperatures.

[0207] See also Fig.25 , Fig.25 The field curvature diagram of the far-infrared optical system 100 provided in Example 3 under infrared light with wavelengths of 8 microns, 10 microns and 12 microns is shown, wherein T1, T2 and T3 are the field curvatures of the infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the meridional direction, respectively, and S1, S2 and S3 are the field curvatures of the infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the sagittal direction, respectively. Fig.25 The horizontal axis is field curvature, and its unit is millimeter. Fig.25 The vertical axis is the field of view angle, and its unit is degree. Fig.25 It can be seen that the meridional field curvature is 0.0183 mm and the sagittal field curvature is 0.0368 mm in the full field of view, which meets the requirements for field curvature in the excellent imaging quality standard.

[0208] See also Fig.26 , Fig.26 The distortion diagram of the far-infrared optical system 100 provided in Example 3 under infrared light with wavelengths of 8 microns, 10 microns and 12 microns is shown. Fig.26 The intervals between the three curves in are too small, so that the three curves almost overlap, and therefore, the three curves are not distinguished. Fig.26 The horizontal axis is the percentage of distortion. Fig.26 The vertical axis is the field of view angle, in degrees. Fig.26 It can be seen that the maximum distortion is 1.07%, which meets the requirements and also meets the distortion requirements of the excellent imaging quality standard.

[0209] See also Fig. 27 , Fig. 27 : shows a relative illumination diagram of the far-infrared optical system 100 provided in Example 3, Fig. 27 The horizontal axis in is the field of view angle, and its unit is degree. Fig. 27 The ordinate in is the relative illumination. Fig. 27 It can be seen that within the entire field of view, the relative illumination is greater than or equal to 90%. Therefore, the brightness of the image plane B is relatively uniform, meeting the requirement for relative illumination in the excellent imaging quality standard.

[0210] See also Fig.28 , Fig.28 The vertical axis chromatic aberration diagram of the far-infrared optical system 100 provided in Example 3 is shown, wherein: Fig.28 The deviation degree of light with a wavelength of 8 microns and a wavelength of 12 microns in the direction perpendicular to the optical axis S is demonstrated based on the position of light with a wavelength of 10 microns on the vertical axis image plane, where the "vertical axis image plane" refers to image plane B. Fig.28 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane B, in microns. Fig.28 The vertical axis is the field of view angle, and its unit is degree. Fig.28 The M1 curve corresponds to light with a wavelength of 8 microns, the M2 curve corresponds to light with a wavelength of 10 microns, and the M3 curve corresponds to light with a wavelength of 12 microns. Fig.28 It can be seen that within the full field of view, the maximum vertical chromatic aberration is about 4.98 microns, which is less than half a pixel. The chromatic aberration is small and the dispersion is not obvious, which meets the chromatic aberration requirements of excellent imaging quality standards.

[0211] See also Fig.29 , Fig.29 The point diagram of the far-infrared optical system 100 provided in Example 3 is shown. Fig.29 It can be seen that within the 0.94 field of view (10.9°), the spot diagrams are all smaller than one pixel, and the light convergence is relatively concentrated.

[0212] See also Fig.30 , Fig.30 : shows a phase curve diagram of the metalens 2 of the far-infrared optical system 100 provided in Example 3, Fig.19 The abscissa of is the radius of the superlens 2, and its unit is millimeter. Fig.30 The ordinate is the phase of the superlens 2, and its unit is 2πrad. Fig.30 It can be seen that the maximum phase difference of the superlens 2 is less than 3.23×2πrad.

[0213] After summarizing the parameters of the far-infrared optical lens 1000 provided in the above three embodiments, the following Table 8 is obtained. Table 8 is mainly used to illustrate that the conditions satisfied by the far-infrared optical lens 1000 provided in this application are all verified and supported by experiments.

[0214] Table 8. Parameters of the far-infrared optical system 100 provided in various embodiments

[0215]

[0216] See also Fig.31 The present application also provides a far-infrared optical lens 1000, which includes an imaging detector (not shown) and the above-mentioned far-infrared optical system 100. 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).

[0217] Please Figure 1 See on the basis of Fig.31 In some embodiments, the far-infrared optical lens 1000 further includes a lens barrel 200, which is substantially cylindrical and is used to encapsulate the far-infrared optical system 100. The lens barrel 200 is provided with a mounting through hole 2001, which is used to provide a mounting space for the far-infrared optical system 100. The mounting through hole 2001 includes a first hole segment 2001a, a second hole segment 2001b, a third hole segment 2001c, and a fourth hole segment 2001d in sequence from the object plane A to the image plane B along the optical axis S, and the first hole segment 2001a, the second hole segment 2001b, the third hole segment 2001c, and the fourth hole segment 2001d are connected in sequence.

[0218] The diameter of the first hole segment 2001a is adapted to the lens diameter of the spherical lens 1, and the diameter of the first hole segment 2001a is larger than the diameter of the second hole segment 2001b, so that the connection transition between the first hole segment 2001a and the second hole segment 2001b is stepped. The spherical lens 1 is accommodated in the first hole segment 2001a, which can prevent the spherical lens 1 from moving toward the image surface B.

[0219] The diameter of the second hole segment 2001b is greater than the diameter of the third hole segment 2001c, so that the connection transition between the second hole segment 2001b and the third hole segment 2001c is in a step shape.

[0220] The diameter of the third hole segment 2001c is adapted to the lens diameter of the aspheric lens 3. The diameter of the third hole segment 2001c is larger than the diameter of the fourth hole segment 2001d, so that the connection transition between the third hole segment 2001c and the fourth hole segment 2001d is stepped. The aspheric lens 3 is accommodated in the third hole segment 2001c, which can prevent the aspheric lens 3 from moving toward the image surface B.

[0221] Please refer again Fig.31 In some embodiments, the far-infrared optical lens 1000 further includes a pressure ring 300 , a first spacer ring 400 and a second spacer ring 500 .

[0222] The pressing ring 300 is generally annular, connected to one end of the lens barrel 200 close to the object surface A, and the pressing ring 300 abuts against the surface of the spherical lens 1 close to the object surface A, so the pressing ring 300 can prevent the spherical lens 1 from moving toward the object surface A, and can fix the spherical lens 1. The connection between the pressing ring 300 and the lens barrel 200 includes but is not limited to threaded connection and bonding.

[0223] The first spacer 400 is generally annular, and is received in the first hole segment 2001a. The first spacer 400 is located on the side of the spherical lens 1 close to the super lens 2. Therefore, the step-like structure at the connection transition between the first hole segment 2001a and the second hole segment 2001b can limit the movement of the first spacer 400 toward the image plane B. Since the first spacer 400 is provided with the spherical lens 1 toward the object plane A, the first spacer 400 can be fixed.

[0224] The second spacer 500 is generally annular, and the second pressure ring 300 is accommodated in the second hole segment 2001b. Therefore, the step-like structure at the connection transition between the second hole segment 2001b and the third hole segment 2001c can prevent the second spacer 500 from moving toward the image plane B. The second spacer 500 also abuts against the first spacer 400, so the second spacer 500 can be fixed. The second spacer 500 abuts against the aspheric lens 3, which can prevent the aspheric lens 3 from moving toward the object plane A, thereby fixing the aspheric lens 3.

[0225] The superlens 2 is disposed between the first spacer 400 and the second spacer 500 , and the first spacer 400 and the second spacer 500 jointly clamp and fix the superlens 2 .

[0226] See also Fig.32 In some embodiments, the first spacer 400 is provided with a fixing through hole 4001a, and the fixing through hole 4001a includes a fifth hole segment 4001a1 and a sixth hole segment 4001a2 which are interconnected, wherein the fifth hole segment 4001a1 is located on a side close to the spherical lens 1.

[0227] The diameter of the sixth hole segment 4001a2 is greater than the diameter of the fifth hole segment 4001a1, so that the connection transition between the sixth hole segment 4001a2 and the fifth hole segment 4001a1 is in a step shape. The diameter of the sixth hole segment 4001a2 is adapted to the lens diameter of the metalens 2, and the metalens 2 is accommodated in the sixth hole segment 4001a2. Therefore, the step structure at the connection transition between the sixth hole segment 4001a2 and the fifth hole segment 4001a1 can limit the movement of the metalens 2 toward the object plane A. The surface of the metalens 2 close to the object plane A abuts against the first spacer 400, and the surface of the metalens 2 close to the image plane B abuts against the second spacer 500, thereby achieving the fixation of the metalens 2.

[0228] Further, the first spacer 400 includes a spacer body 4001 and an abutment portion 4002, and the fixing through hole 4001a is provided in the spacer body 4001. The abutment portion 4002 is connected to the side of the spacer body 4001 facing the aspheric lens 3, and the abutment portion 4002 is provided around the sixth hole segment 4001a2. The abutment portion 4002 abuts against the second spacer 400, so the abutment portion 4002 can reduce the clamping force on the super lens 2, and can reduce the probability of the super lens 2 being damaged due to excessive clamping force.

[0229] 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: a spherical lens, a super lens and an aspherical lens in sequence from the object side to the image side along the optical axis; the spherical lens has positive optical power, the curvature radius of the surface of the spherical lens close to the object side is positive, and the curvature radius of the surface of the spherical lens close to the image side is positive; the super lens has positive optical power; the aspherical lens has positive optical power, the surface of the aspherical lens close to the object side is convex to the image side, and the surface of the aspherical lens close to the image side is convex to the image side, the refractive index of the aspherical lens is equal to the refractive index of the spherical lens, and the Abbe number of the aspherical lens is equal to the Abbe number of the spherical lens.

2. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, fno is the aperture number of the far-infrared optical system, D is the effective diameter of the surface of the spherical lens close to the object side, TTL is the total optical length of the far-infrared optical system, and R 11 is the radius of curvature of the surface of the spherical lens close to the object side, and the R 12 is the radius of curvature of the surface of the spherical lens close to the image side, and the R 31 is the radius of curvature of the surface of the aspheric lens close to the object side, and the R 32 is the radius of curvature of the surface of the aspheric lens close to the image side.

3. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 0.45<SAG 31 / SAG 32 <0.55, wherein the intersection of the surface of the aspheric lens close to the object side and the optical axis is the first point, and the SAG 31 is the distance between the first point and the vertex of the effective radius of the surface of the aspheric lens close to the object side on the optical axis, the intersection of the surface of the aspheric lens close to the image side and the optical axis is the second point, and the SAG 32 is the distance between the second point and the vertex of the effective radius of the surface of the aspheric lens close to the image side on the optical axis.

4. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 0.03<(f1-f3) / f2<0.06, wherein f1 is the focal length of the spherical lens, f2 is the focal length of the super lens, and f3 is the focal length of the aspherical lens.

5. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 4.1mm<f×CT1 / R 11 <4.9mm, wherein f is the effective focal length of the far-infrared optical system, CT1 is the center thickness of the spherical lens, and R 11 is the radius of curvature of the surface of the spherical lens close to the object side.

6. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 0.40<BFL / f<0.48, wherein the BFL is the distance between the center of the surface of the aspherical lens close to the image side and the image plane of the far-infrared optical system, and f is the effective focal length of the far-infrared optical system.

7. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 0.95<(CT 12 -ET 12 ) / (CT 23 -ET 23 )<1.05, wherein the CT 12 is the distance between the surface of the spherical lens close to the image side and the surface of the super lens close to the object side on the optical axis, and the ET 12 is the distance between the edge of the surface of the spherical lens close to the image side and the edge of the surface of the super lens close to the object side along the direction parallel to the optical axis; the CT 23 is the distance between the surface of the super lens close to the image side and the surface of the aspheric lens close to the object side on the optical axis, and the ET 23 is the distance between the edge of the surface of the super lens close to the image side and the edge of the surface of the aspheric lens close to the object side along the direction parallel to the optical axis.

8. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 1.05<D / EPD<1.25, wherein D is the effective diameter of the surface of the spherical lens close to the object side, and the EPD is the entrance pupil diameter of the far-infrared optical system.

9. The far-infrared optical system according to claim 1, characterized in that: The metalens satisfies the conditional formula with 2π radians per millimeter as a unit: The R M is the effective radius of the superlens, is the maximum phase difference of the metalens within the effective radius.

10. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 0.6<(ET1+ET2+ET3) / (CT1+CT2+CT3)<0.8, wherein the ET1 is the edge thickness of the spherical lens, the ET2 is the edge thickness of the super lens, the ET3 is the edge thickness of the aspherical lens, the CT1 is the center thickness of the spherical lens, the CT2 is the center thickness of the super lens, and the CT3 is the center thickness of the aspherical lens.

11. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 1.7<CT 12 / CT 23 <2.5, wherein the CT 12 is the distance between the surface of the spherical lens close to the image side and the surface of the super lens close to the object side on the optical axis, and the CT 23 is the distance between the surface of the super lens close to the image side and the surface of the aspheric lens close to the object side on the optical axis.

12. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system satisfies: 0.270<BFL / TTL<0.285, wherein the BFL is the distance between the center of the surface of the aspherical lens close to the image side and the image plane of the far-infrared optical system, and the TTL is the total optical length of the far-infrared optical system.

13. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: 1.40<f1 / f<1.50; 9.5<f2 / f<14.5; 0.9<f3 / f<0.95; Among them, f1 is the focal length of the spherical lens, f2 is the focal length of the super lens, f3 is the focal length of the aspherical lens, and f is the effective focal length of the far-infrared optical system.

14. The far-infrared optical system according to any one of claims 1 to 13, characterized in that: The far-infrared optical system further includes an aperture, which is disposed between the spherical lens and the super lens.

15. A far-infrared optical lens, characterized in that: include: An imaging detector and a far-infrared optical system as claimed in any one of claims 1 to 14; The imaging detector is arranged on the image plane of the far-infrared optical system.

16. The far-infrared optical lens according to claim 15, characterized in that: The far-infrared optical lens also includes a lens barrel, the lens is provided with a mounting through hole, the mounting through hole includes a first hole segment, a second hole segment, a third hole segment and a fourth hole segment that are sequentially connected along the optical axis from the object side to the image side, the diameter of the first hole segment is larger than the diameter of the second hole segment, the diameter of the second hole segment is larger than the diameter of the third hole segment, and the diameter of the third hole segment is larger than the diameter of the fourth hole segment; The spherical lens is accommodated in the first hole segment; the aspherical lens is accommodated in the third hole segment.

17. The far-infrared optical lens according to claim 16, characterized in that: The far-infrared optical lens also includes a pressure ring, a first spacer ring and a second spacer ring. The pressing ring is connected to the lens barrel, and the pressing ring abuts against the surface of the spherical lens close to the object side; The first spacer is accommodated in the first hole section, and the first spacer is located on the side of the spherical lens close to the super lens; the second spacer is accommodated in the second hole section, and the second spacer is respectively abutted against the first spacer and the aspherical lens; the super lens is arranged between the first spacer and the second spacer.

18. The far-infrared optical lens according to claim 17, characterized in that: The first spacer ring is provided with a fixed through hole, and the fixed through hole includes a fifth hole segment and a sixth hole segment which are interconnected, the diameter of the sixth hole segment is larger than the diameter of the fifth hole segment, the superlens is accommodated in the sixth hole segment, the surface of the superlens close to the object side abuts against the first spacer ring, and the surface of the superlens close to the image side abuts against the second spacer ring.

Images