Far infrared optical system and far infrared optical lens

Abstract

The invention discloses a far infrared optical system and a far infrared optical lens. The far infrared optical system sequentially comprises a first refractor, a super lens and a second refractor from an object side to an image side along an optical axis, the focal power of the first refraction lens is positive, the object side face of the first refraction lens protrudes towards the object side, and the image side face of the first refraction lens protrudes towards the object side; the focal power of the super lens is positive; the second refraction lens is an aspherical lens, the focal power of the second refraction lens is positive, the object side surface of the second refraction lens protrudes towards the image side, and the image side surface of the second refraction lens protrudes towards the image side; and the far infrared optical system satisfies # imgabs 0 #, wherein # imgabs 1 # is the maximum phase difference of the super lens. The far infrared optical system has the advantages of being low in cost, large in aperture and excellent in imaging quality, and the far infrared optical system further has the advantage of athermalization, so that the far infrared optical system can adapt to various environments.

Description

Technical Field

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

[0002] Objects above absolute zero (0K, i.e. -273.15℃) will automatically radiate far-infrared light. Since far-infrared optical systems can form images in dark environments without the need for supplemental light, they are widely used in many fields.

[0003] Image quality has always been one of the goals pursued by far-infrared optical systems. However, in order to correct aberrations, it is usually achieved by using multiple lenses or using expensive germanium lenses in the prior art. However, using multiple lenses or using germanium lenses will cause the far-infrared optical system to have problems such as high cost and large volume. At the same time, some far-infrared optical systems in the prior art also have the problem that the image quality is greatly affected by temperature. The above problems seriously restrict the widespread application of far-infrared optical systems. Summary of the invention

[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, aiming to solve at least one of the above problems.

[0005] According to one aspect of an embodiment of the present application, a far-infrared optical system is disclosed, and the far-infrared optical system includes, in order from the object side to the image side along the optical axis: a first refractive lens, a super lens, and a second refractive lens; the optical focal power of the first refractive lens is positive, the object side surface of the first refractive lens is convex toward the object side, and the image side surface of the first refractive lens is convex toward the object side; the optical focal power of the super lens is positive; the second refractive lens is an aspherical lens, the optical focal power of the second refractive lens is positive, the object side surface of the second refractive lens is convex toward the image side, and the image side surface of the second refractive lens is convex toward the image side;

[0006] The far-infrared optical system meets the following requirements: Among them, the is the maximum phase difference of the superlens.

[0007] In some embodiments, the far-infrared optical system satisfies: Among them, the is the phase of the metalens, r is the radius of the metalens, FNO is the aperture number of the far-infrared optical system, and D meta is the maximum effective diameter of the metalens, and the BFL is the optical back focus of the far-infrared optical system.

[0008] In some embodiments, the far-infrared optical system satisfies: Among them, the SAG 31 is the sag height of the object side surface of the second refractive lens, the SAG 32 is the sagittal height of the image side surface of the second refractive lens, and f3 is the focal length of the second refractive lens.

[0009] In some embodiments, the far-infrared optical system satisfies: Among them, the FOV is the maximum field angle of the far-infrared optical system, the D1 is the maximum effective diameter of the object side of the first refractive lens, and the EPD is the entrance pupil diameter of the far-infrared optical system.

[0010] In some embodiments, the far-infrared optical system satisfies: Among them, the R 11 is the radius of curvature of the object side surface of the first refractive lens, and the R 12 is the curvature radius of the image-side surface of the first refractive lens, and f1 is the focal length of the first refractive lens.

[0011] In some embodiments, the far-infrared optical system satisfies: Among them, the BFL is the optical back focus of the far-infrared optical system, and f is the effective focal length of the far-infrared optical system.

[0012] In some embodiments, the far-infrared optical system satisfies: Wherein, f1 is the focal length of the first refractive lens, f3 is the focal length of the second refractive lens, and SAG 11 is the sag height of the object side surface of the first refractive lens, the SAG 12 is the sagittal height of the image side surface of the first refractive lens, the SAG 31 is the sag height of the object side surface of the second refractive lens, the SAG 32 is the sagittal height of the image-side surface of the second refractive lens.

[0013] In some embodiments, the far-infrared optical system satisfies: Among them, the TTL is the total optical length of the far-infrared optical system, the FNO is the aperture number of the far-infrared optical system, the D1 is the maximum effective diameter of the object side of the first refractive lens, the EPD is the entrance pupil diameter of the far-infrared optical system, and the n1 is the refractive index of the first refractive lens.

[0014] In some embodiments, the far-infrared optical system satisfies: The BFL is the optical back focus of the far-infrared optical system, and the SAG 32is the sagittal height of the image side surface of the second refractive lens, and CT3 is the central thickness of the second refractive lens.

[0015] In some embodiments, the far-infrared optical system further includes an aperture, and the aperture is disposed on the object side of the first refractive lens; or, the aperture is disposed between any two adjacent lenses.

[0016] A second aspect of an embodiment of the present application provides a far-infrared optical lens, which includes: an imaging detector and a far-infrared optical system as described in any one of the above items; the imaging detector is arranged on the image plane of the far-infrared optical system.

[0017] The far-infrared optical system provided by the present application comprises, in order from the object side to the image side along the optical axis: a first refractive lens, a super lens, and a second refractive lens; the optical power of the first refractive lens is positive, the object side surface of the first refractive lens is convex to the object side, and the image side surface of the first refractive lens is convex to the object side; the optical power of the super lens is positive; the second refractive lens is an aspherical lens, the optical power of the second refractive lens is positive, the object side surface of the second refractive lens is convex to the image side, and the image side surface of the second refractive lens is convex to the image side; the far-infrared optical system satisfies: in, is the maximum phase difference of the metalens. The far-infrared optical system provided by the present application has a large aperture, and the imaging quality of the far-infrared optical system is excellent. The far-infrared optical system has a small number of lenses and a short total optical length, which makes the far-infrared optical system small in size and low in production cost. In addition, the far-infrared optical system includes a metalens, and the production cost of the metalens is low, which can further reduce the production cost of the far-infrared optical system. The far-infrared optical system also has the advantage of being athermal, so that it can adapt to a variety of environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] Figure 1 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0020] Figure 2 The phase distribution diagram of the metalens of the far-infrared optical system in one embodiment of the present application is shown.

[0021] Figure 3 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0022] Figure 4 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0023] Figure 5 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0024] Figure 6 A field curvature curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0025] Figure 7 A distortion curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0026] Figure 8 A vertical axis chromatic aberration curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0027] Fig. 9 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0028] Fig.10 The phase distribution diagram of the metalens of the far-infrared optical system in one embodiment of the present application is shown.

[0029] Fig.11 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0030] Fig.12 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0031] Fig.13 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0032] Fig.14 A field curvature curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0033] Fig.15 A distortion curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0034] Fig.16 A vertical axis chromatic aberration curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0035] Fig.17 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0036] Fig.18 The phase distribution diagram of the metalens of the far-infrared optical system in one embodiment of the present application is shown.

[0037] Fig.19The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0038] Fig. 20 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0039] Fig.21 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0040] Fig. 22 A field curvature curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0041] Fig.23 A distortion curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0042] Fig.24 A vertical axis chromatic aberration curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0043] Fig.25 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0044] Fig.26 The phase distribution diagram of the metalens of the far-infrared optical system in one embodiment of the present application is shown.

[0045] Fig. 27 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0046] Fig.28 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0047] Fig.29 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0048] Fig.30 A field curvature curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0049] Fig.31 A distortion curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0050] Fig.32 A vertical axis chromatic aberration curve diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0051] Reference numerals

[0052] 100. Far infrared optical system;

[0053] 10. a first refractive lens;

[0054] 20. Super lens; 210. Substrate; 220. Micro-nano structure;

[0055] 30. a second refractive lens;

[0056] 40. Aperture;

[0057] 50. Protective glass;

[0058] 60. Object surface;

[0059] 70. Image plane;

[0060] 80. Optical axis. DETAILED DESCRIPTION

[0061] 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.

[0062] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other modules, components, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application obscure.

[0063] 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 80 is the center line of the light beam. Figure 1 In the figure, the object to be measured is located on the left side of the leftmost lens, that is, the object side is located on the left side of the leftmost lens, and the object plane 60 is located on the object side. The image formed by the far-infrared optical system 100 is located on the right side of the rightmost lens, that is, the image side is located on the right side of the rightmost lens, and the image plane 70 is located on the image side. Therefore, the direction from the object plane 60 to the image plane 70 along the optical axis 80 is consistent with the direction from the object side to the image side along the optical axis 80.

[0064] The side of each optical element of the far-infrared optical system 100 close to the object side is the object side of the corresponding optical element, and the side of each optical element of the far-infrared optical system 100 close to the image side is the image side of the corresponding optical element. The surface of each optical element of the far-infrared optical system 100 close to the object side is the object side surface of the corresponding optical element, and the surface of each optical element of the far-infrared optical system 100 close to the image side is the image side surface of the corresponding optical element.

[0065] The far-infrared optical system 100 includes a first refractive lens 10 , a super lens 20 , and a second refractive lens 30 , which are sequentially arranged along the optical axis 80 from the object side to the image side.

[0066] The optical power of the first refractive lens 10 is positive, the object side surface of the first refractive lens 10 is convex toward the object side, and the image side surface of the first refractive lens 10 is convex toward the object side, that is, the first refractive lens 10 is a meniscus lens.

[0067] The optical power of the super lens 20 is positive. The super lens 20 includes a substrate 210 and a micro-nano structure 220 , wherein the micro-nano structure 220 is disposed on the image side surface and / or the object side surface of the substrate 210 .

[0068] The second refractive lens 30 is an aspherical lens, and the optical power of the second refractive lens 30 is positive. The object side surface of the second refractive lens 30 is convex toward the image side, and the image side surface of the second refractive lens 30 is convex toward the image side.

[0069] The far-infrared optical system 100 satisfies conditional formula 1: in, is the maximum phase difference of the superlens 20. The superlens 20 in the far-infrared optical system 100 satisfies the conditional formula 1, so that the superlens 20 can provide negative dispersion in the far-infrared optical system 100, which is beneficial to control the dispersion of the far-infrared optical system 100.

[0070] The far-infrared optical system 100 provided by the present application has a large aperture, and the imaging quality of the far-infrared optical system 100 is excellent. The number of lenses of the far-infrared optical system 100 is small, and the total optical length is short, so that the far-infrared optical system 100 has a small volume and a low production cost. In addition, the far-infrared optical system 100 includes a super lens 20, and the production cost of the super lens 20 is low, which can further reduce the production cost of the far-infrared optical system 100. The far-infrared optical system 100 also has the advantage of being athermal, so that it can adapt to a variety of environments.

[0071] Compared with the far-infrared optical system in the prior art, the far-infrared optical system 100 provided in the present application has fewer lenses and does not use expensive germanium lenses, but the far-infrared optical system 100 can still take into account the advantages of large aperture, low cost, small size and no heat generation.

[0072] It should be noted that the modulation effect of the metalens 20 on the light is determined by the phase of the metalens 20. According to the principle of phase superposition, the target phase can be provided by one, two or more metalens 20. Therefore, the present application does not limit the number of metalens 20, as long as the sum of the phases of all metalens 20 in the far-infrared optical system 100 is equal to the target phase. Exemplarily, the target phase is a×2πrad, and a phase of a×2πrad can be provided by one metalens 20, or by two or more metalens 20, as long as the sum of the phases of each metalens 20 is equal to a×2πrad.

[0073] In some embodiments, the first refractive lens 10 is a spherical lens. Since the production cost of a spherical lens is relatively low, it is helpful to further reduce the production cost of the far-infrared optical system 100.

[0074] In some embodiments, the first refractive lens 10 is an aspherical lens, which is beneficial to reducing the aberration of the far-infrared optical system 100 and improving the imaging quality of the far-infrared optical system 100 .

[0075] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 2: in, is the phase of the superlens, r is the radius of the superlens, is the phase gradient of the metalens, is the maximum absolute value of the phase gradient of the metalens 20, The unit is rad / mm. FNO is the aperture number of the far-infrared optical system 100, that is, FNO is the F number of the far-infrared optical system 100. meta is the maximum effective diameter of the metalens 20, and BFL (Back focal length, referred to as BFL) is the optical back focal length of the far-infrared optical system 100. Specifically, BFL is equal to the distance between the image side surface of the second refractive lens 30 and the image plane 70 on the optical axis 80. BFL, D meta have the same dimension, which is a unit of length, such as millimeter.

[0076] Conditional formula 1 can ensure that the far-infrared optical system 100 can effectively correct chromatic aberration and aperture-related aberrations under the premise of having a large aperture. At the same time, conditional formula 1 also constrains the phase change of the super lens 20, which can reduce the tolerance sensitivity of the super lens 20, making the super lens 20 easy to process.

[0077] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 3: Among them, SAG 31 is the sag height of the object side surface of the second refractive lens 30, SAG32 is the sagittal height of the image side surface of the second refractive lens 30, and f3 is the focal length of the second refractive lens 30. 31 、SAG 32 , f3 have the same dimension, both are length units, such as millimeters.

[0078] Conditional expression 3 can ensure that the negative spherical aberration generated on the object side of the second refractive lens 30 and the positive spherical aberration generated on the image side of the second refractive lens 30 cancel each other out, thereby reducing the influence of spherical aberration on the imaging quality of the far-infrared optical system 100 .

[0079] In some embodiments, the far-infrared optical system 100 satisfies Condition 4: Wherein, FOV (Field of View, referred to as FOV) is the maximum field of view angle of the far-infrared optical system 100, and its unit is degree. D1 is the maximum effective diameter of the object side of the first refractive lens 10. In the present application, the maximum effective diameter of the lens is the diameter of the maximum light-transmitting area of ​​the lens, and the same applies below. EPD (Entrance Pupil Diameter, referred to as EPD) is the entrance pupil diameter of the far-infrared optical system 100. D1 and EPD have the same dimension, both are length units, such as millimeters.

[0080] Conditional expression 4 can improve the light energy utilization rate of the far-infrared optical system 100, increase the light receiving area, make the light fill the entire image plane 70, and further improve the relative illumination of the edge of the picture.

[0081] In some embodiments, the far-infrared optical system 100 satisfies Condition 5: Among them, R 11 is the radius of curvature of the object side surface of the first refractive lens 10, R 12 R is the curvature radius of the image side surface of the first refractive lens 10, and f1 is the focal length of the first refractive lens 10. 11 , R 12 , f1 have the same dimension, both are length units, such as millimeters.

[0082] Conditional expression 5 is used to control the aperture and shape of the first refractive lens 10 , which can reduce the distortion of the far-infrared optical system 100 and is beneficial to improving the aberration of the far-infrared optical system 100 .

[0083] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 6: Wherein, BFL is the optical back focus of the far-infrared optical system 100, and f is the effective focal length of the far-infrared optical system 100. BFL and f have the same dimension, both of which are length units, such as millimeters.

[0084] Conditional formula six reflects the ratio of the optical back focus to the effective focal length of the far-infrared optical system 100. Since the length of the optical back focus has a certain influence on the total optical length of the far-infrared optical system 100, conditional formula six can ensure that the far-infrared optical system 100 has a smaller total optical length while meeting the effective focal length, so that the far-infrared optical system 100 can be miniaturized.

[0085] In some embodiments, the far-infrared optical system 100 satisfies conditional equation 7: Wherein, f1 is the focal length of the first refractive lens 10, f3 is the focal length of the second refractive lens 30, SAG 11 is the sag height of the object side surface of the first refractive lens 10, SAG 12 is the sagittal height of the image side surface of the first refractive lens 10, SAG 31 is the sag height of the object side surface of the second refractive lens 30, SAG 32 is the sagittal height of the image side surface of the second refractive lens 30. f1, f3, SAG 11 、SAG 12 、SAG 31 、SAG 32 have the same dimension, which is a unit of length, such as millimeter.

[0086] Conditional expression 7 can ensure that the optical focal length of the first refractive lens 10 and the second refractive lens 30 in the far-infrared optical system 100 is reasonably distributed, and can avoid the optical focal length being concentrated on a certain refractive lens. If the optical focal length is concentrated on a certain refractive lens, the far-infrared optical system 100 will have a problem of greater tolerance sensitivity. That is, conditional expression 7 can reduce the tolerance sensitivity of the far-infrared optical system 100, and thus improve the processing and assembly yield of the far-infrared optical system 100.

[0087] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 8: Wherein, TTL is the total optical length of the far-infrared optical system 100; FNO is the aperture number of the far-infrared optical system 100, that is, FNO is the F number of the far-infrared optical system 100; D1 is the maximum effective diameter of the object side of the first refractive lens 10, EPD is the entrance pupil diameter of the far-infrared optical system 100, and n1 is the refractive index of the first refractive lens 10 at a central wavelength of 10 microns. TTL, D1, and EPD have the same dimension, which are all length units, such as millimeters.

[0088] Conditional expression eight can ensure that the far-infrared optical system 100 increases the amount of light as much as possible while having excellent imaging quality, so that the far-infrared optical system 100 can collect more light, thereby ensuring the brightness of the picture.

[0089] In some embodiments, the far-infrared optical system 100 satisfies Condition 9: BFL is the optical back focus of the far-infrared optical system 100, SAG 32 is the sagittal height of the image side surface of the second refractive lens 30; CT3 is the central thickness of the second refractive lens 30, that is, CT3 is the thickness of the second refractive lens 30 on the optical axis 80. BFL, SAG 32 , CT3 have the same dimension, both are length units, such as millimeters.

[0090] Conditional formula 9 effectively constrains the thickness and surface shape of the second refractive lens 30, and ensures the optical back focus length of the far-infrared optical system 100, ensuring that the far-infrared optical system 100 has a long optical back focus under the premise of having excellent imaging quality, thereby reserving sufficient installation space for the shutter assembly located between the far-infrared optical system 100 and the image plane 70. At the same time, conditional formula 9 constrains the thickness and surface shape of the second refractive lens 30, which can effectively reduce the volume of the second refractive lens 30, and can reduce the material usage of the second refractive lens 30 to reduce production costs.

[0091] The far-infrared optical system 100 further includes an aperture 40, which is used to control the amount of light entering the far-infrared optical system 100, thereby ensuring that the far-infrared optical system 100 can work effectively and generate high-quality images.

[0092] In some embodiments, the aperture 40 is disposed on the object side of the first refractive lens 10. Specifically, the aperture 40 may be disposed at any of the following positions:

[0093] (1) The aperture 40 is disposed on the object side of the first refractive lens 10, and the aperture 40 is spaced apart from the first refractive lens 10;

[0094] (2) The aperture 40 is disposed on the object side surface of the first refractive lens 10 , that is, the aperture 40 is disposed in contact with the object side surface of the first refractive lens 10 .

[0095] In some embodiments, the aperture 40 is disposed between any two adjacent lenses. Specifically, the aperture 40 may be disposed at any of the following positions:

[0096] (1) The aperture 40 is disposed between the first refractive lens 10 and the metalens 20, and the aperture 40 is disposed on the image side surface of the first refractive lens 10;

[0097] (2) The aperture 40 is disposed between the first refractive lens 10 and the super lens 20, and the aperture 40 is spaced apart from the first refractive lens 10 and the super lens 20;

[0098] (3) The aperture 40 is disposed between the first refractive lens 10 and the super lens 20, and the aperture 40 is disposed on the object side surface of the super lens 20;

[0099] (4) The aperture 40 is disposed between the super lens 20 and the second refractive lens 30, and the aperture 40 is disposed on the image side surface of the super lens 20;

[0100] (5) The aperture 40 is disposed between the super lens 20 and the second refractive lens 30, and the aperture 40 is spaced apart from the super lens 20 and the second refractive lens 30;

[0101] (6) The aperture 40 is disposed between the super lens 20 and the second refractive lens 30 , and the aperture 40 is disposed on the object-side surface of the second refractive lens 30 .

[0102] Furthermore, in some embodiments, the aperture 40 is located between the first refractive lens 10 and the superlens 20, so that the aperture 40 can limit the light in the edge field of view from entering the far-infrared optical system 100, which is beneficial to improving the imaging quality of the far-infrared optical system 100; and, because the aperture 40 limits the light in the edge field of view from entering the far-infrared optical system 100, the superlens 20 located on the image side of the aperture 40 has a smaller aperture, which can reduce the production cost of the superlens 20, and further reduce the production cost of the far-infrared optical system 100.

[0103] In some embodiments, the far-infrared optical system 100 also includes a protective glass 50, which is disposed between the second refractive lens 30 and the image plane 70. An imaging detector matching the far-infrared optical system 100 is disposed on the image plane 70. The protective glass 50 can reduce the probability of the imaging detector being damaged.

[0104] The far-infrared optical system 100 provided by the present application has the following benefits:

[0105] (1) The F number is less than 1.0;

[0106] (2) Distortion is less than 1%;

[0107] (3) Relative illumination greater than 90%;

[0108] (4) Total optical length (TTL) less than 19 mm;

[0109] (5) optical back focus (BFL) greater than 6 mm;

[0110] (6) It has good heat elimination effect in the range of -40℃~80℃.

[0111] The present application exemplarily provides four far-infrared optical systems 100 that meet usage requirements in four embodiments. Next, the far-infrared optical systems 100 provided in the various embodiments of the present application are introduced in detail.

[0112] Example 1

[0113] Figure 1FIG. 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, along the optical axis 80, from the object plane 60 to the image plane 70, a first refractive lens 10, an aperture 40, a super lens 20, a second refractive lens 30, and a protective glass 50, wherein the first refractive lens 10 is a spherical lens, and the micro-nano structure 220 is disposed on the object side of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Example 1 are shown in Table 1-1.

[0114] Table 1-1. Partial parameters of the far-infrared optical system 100 provided in Example 1

[0115]

[0116]

[0117] As can be seen from Table 1-1, the working band of the far-infrared optical system 100 is 8 μm-12 μm, the total optical length of the far-infrared optical system 100 is relatively short, which is 19 mm, and the volume of the far-infrared optical system 100 provided in Example 1 is relatively small. The F number of the far-infrared optical system 100 is 0.947, and the far-infrared optical system 100 has a large amount of light input.

[0118] Along the direction of the optical axis 80 from the object plane 60 to the image plane 70, starting from the object plane 60, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 1-2.

[0119] Table 1-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 1

[0120] Surface number Optical Components Surface type Curvature radius (mm) Thickness(mm) Material 0 flat unlimited unlimited - 1 First refractive lens Spherical 10.836 4.113 Chalcogenide glass 2 Spherical 13.103 3.977 - 3 Aperture flat unlimited 0.181 - 4 Super Lens Structural surface unlimited 0.300 silicon 5 flat unlimited 1.115 - 6 Second refractive lens even aspherical surface -10.218 3.233 Chalcogenide glass 7 even aspherical surface -9.127 5.481 - 8 Protective glass flat unlimited 0.500 silicon 9 flat unlimited 0.100 - 10 flat unlimited - -

[0121] For each surface in Table 1-2, surface 0 is the object surface 60, surface 1 is the object side surface of the first refractive lens 10, and surface 2 is the image side surface of the first refractive lens 10. Surface 3 is the aperture 40, and surface 4 is the object side surface of the super lens 20. Since the micro-nano structure 220 is arranged on the object side surface of the substrate 210, that is, the micro-nano structure 220 is located on surface 4, surface 4 is recorded as the structural surface, and surface 5 is the image side surface of the super lens 20. Surface 6 is the object side surface of the second refractive lens 30, and surface 7 is the image side surface of the second refractive lens 30. Surface 8 is the object side surface of the protective glass 50, surface 9 is the image side surface of the protective glass 50, and surface 10 is the image surface 70.

[0122] As can be seen from Table 1-2, surface 1 is a spherical surface, the radius of curvature of surface 1 is 10.836 mm, the distance between surface 1 and surface 2 is 4.113 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 13.103 mm, the distance between surface 2 and surface 3 is 3.977 mm, and the material between surface 2 and surface 3 is air. Surface 3 is a plane, the distance between surface 3 and surface 4 is 0.181 mm, and the material between surface 3 and surface 4 is air. 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. Surface 5 is a plane, the distance between surface 5 and surface 6 is 1.115 mm, and the material between surface 5 and surface 6 is air. Surface 6 is an even aspheric surface, the radius of curvature of surface 6 is -10.218 mm, the distance between surface 6 and surface 7 is 3.233 mm, and the material between surface 6 and surface 7 is chalcogenide glass. Surface 7 is an even aspheric surface, the radius of curvature of surface 7 is -9.127 mm, the distance between surface 7 and surface 8 is 5.481 mm, and the material between surface 7 and surface 8 is air. Surface 8 is a plane, the distance between surface 8 and surface 9 is 0.500 mm, and the material between surface 8 and surface 9 is silicon. Surface 9 is a plane, the distance between surface 9 and surface 10 is 0.100 mm, and the material between surface 9 and surface 10 is air.

[0123] Surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0124]

[0125] 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 80; c is the curvature of the aspherical surface, c=1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 6 and surface 7 can be obtained from Table 1-3.

[0126] Table 1-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 1

[0127] Surface number k A B C D E F 6 3.845 1.064E-3 -4.164E-4 6.033E-5 -4.661E-6 1.965E-7 -3.374E-9 7 -3.341 -5.920E-4 -2.809E-5 2.784E-6 -9.489E-8 8.878E-10 1.040E-11

[0128] Refer to Table 1-3. For surface 6, k is 3.845, A is 1.064E-3, B is -4.164E-4, C is 6.033E-5, D is -4.661E-6, E is 1.965E-7, and F is -3.374E-9. The coefficients of the even-order aspheric surface of surface 7 can be obtained from Table 1-3, and will not be elaborated here one by one.

[0129] See also Figure 2 , Figure 2 : shows a phase distribution diagram of the super lens 20 of the far-infrared optical system 100 provided in Example 1, Figure 2 The horizontal axis represents the distance from the center of the superlens 20. Figure 2 The vertical axis represents the phase. Figure 2 It can be seen that the absolute value of the maximum phase difference of the super lens 20 is is 3.39×2πrad. It is worth mentioning that Figure 2 The actual phase distribution of the superlens 20 in Example 1 is given. Since the phase is a periodic function about 2π, there is a relationship: (n is an integer), so it can be based on Figure 2 The phase of the superlens 20 in Example 1 is modulo 2π to achieve normalization processing to meet the needs of actual processing of the superlens 20.

[0130] See also Figure 3 , Figure 3 The MTF (Modulation Transfer Function, MTF for short) field of view curve of the far-infrared optical system 100 provided in Example 1 at 20° C. is shown. Figure 3 The abscissa in is the image height, and its unit is millimeter; Figure 3 The vertical axis is the MTF value. Figure 3 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Figure 3 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.39, and the imaging quality of the far-infrared optical system 100 is excellent.

[0131] See also Figure 4 , Figure 4 The MTF field curve of the far-infrared optical system 100 provided in Example 1 at -40°C is shown. Figure 4 The abscissa in is the image height, and its unit is millimeter; Figure 4 The vertical axis is the MTF value. Figure 4 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Figure 4It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is excellent.

[0132] See also Figure 5 , Figure 5 The MTF field curve of the far-infrared optical system 100 provided in Example 1 at 80° C. is shown. Figure 5 The abscissa in is the image height, and its unit is millimeter; Figure 5 The vertical axis is the MTF value. Figure 5 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Figure 5 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.28, and the imaging quality of the far-infrared optical system 100 is excellent.

[0133] comprehensive Figures 3 to 5 It can be seen that when the temperature changes within the range of -40°C-80°C, the MTF value changes slightly. Therefore, the far-infrared optical system 100 provided in Example 1 has a good athermalization effect and meets the athermalization requirement.

[0134] See also Figure 6 , Figure 6 1 shows a field curvature curve diagram of the far-infrared optical system 100 provided in Example 1, Figure 6 The central horizontal axis is the field curvature, which is in millimeters; Figure 6 The vertical axis is the field of view angle, and its unit is degree. Figure 6 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Figure 6 It can be seen that the field curvature of the far-infrared optical system 100 in the sagittal direction within the full field of view is 0.0573 mm, and the field curvature of the far-infrared optical system 100 in the meridional direction within the full field of view is 0.1127 mm. The field curvature is small, meeting the requirements for field curvature in the excellent imaging quality standard.

[0135] See also Figure 7 , Figure 7 The distortion curves of the far-infrared optical system 100 provided in Example 1 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns are shown. Figure 7The horizontal axis is distortion, in percentage; Figure 7 The vertical axis is the field of view, and its unit is degree. Figure 7 The distances between the distortion curves of far-infrared light with medium wavelengths of 8 microns, 10 microns, and 12 microns are extremely small, making it difficult to distinguish between the three curves. Therefore, this embodiment does not distinguish between the three curves. Figure 7 It can be seen that the maximum distortion of the far-infrared optical system 100 provided in Example 1 is 0.83%, which is relatively small and meets the requirement of clear imaging.

[0136] See also Figure 8 , Figure 8 The vertical axis chromatic aberration curve of the far-infrared optical system 100 provided in Example 1 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns is shown. Figure 8 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane 70, in millimeters; Figure 8 The vertical axis is the field of view angle, and its unit is degree. Figure 8 There are three curves in total, among which the W2 curve located at 0 microns on the horizontal axis is the far-infrared light with a wavelength of 10 microns, the W1 curve is the far-infrared light with a wavelength of 8 microns, and the W3 curve is the far-infrared 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 between different wavelengths is less than 8 microns, the chromatic aberration is small, and the dispersion is not obvious.

[0137] Example 2

[0138] Fig. 9 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 2. Fig. 9 The mid-infrared optical system 100 includes, along the optical axis 80, from the object plane 60 to the image plane 70, a first refractive lens 10, an aperture 40, a super lens 20, a second refractive lens 30, and a protective glass 50, wherein the first refractive lens 10 is a spherical lens, and the micro-nano structure 220 is disposed on the object side of the substrate 210. Some parameters of the far-infrared optical system 100 provided in Example 2 are shown in Table 2-1.

[0139] Table 2-1. Partial parameters of the far-infrared optical system 100 provided in Example 2

[0140]

[0141]

[0142] As can be seen from Table 2-1, the operating band of the far-infrared optical system 100 is 8 μm-12 μm, the total optical length of the far-infrared optical system 100 is relatively short, which is 19 mm, and the volume of the far-infrared optical system 100 provided in Example 2 is relatively small. The F number of the far-infrared optical system 100 is 0.9476, and the far-infrared optical system 100 has a large amount of light input.

[0143] Along the direction of the optical axis 80 from the object plane 60 to the image plane 70, starting from the object plane 60, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 2-2.

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

[0145] Surface number Optical Components Surface type Curvature radius (mm) Thickness(mm) Material 0 flat unlimited unlimited - 1 First refractive lens Spherical 10.560 4.621 Chalcogenide glass 2 Spherical 11.752 3.445 - 3 Aperture flat unlimited 0.182 - 4 Super Lens Structural surface unlimited 0.300 silicon 5 flat unlimited 1.144 - 6 Second refractive lens even aspherical surface -11.111 3.223 Chalcogenide glass 7 even aspherical surface -9.496 5.485 - 8 Protective glass flat unlimited 0.500 silicon 9 flat unlimited 0.100 - 10 flat unlimited - -

[0146] The analysis of each surface in Table 2-2 can refer to Example 1, and this example does not analyze each surface again.

[0147] Surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0148]

[0149] Among them, Z(r) is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of r along the optical axis 80; c is the curvature of the aspheric surface, c = 1 / R, R is the radius of curvature of the aspheric surface; k is the cone coefficient; A, B, C, D... are the aspheric coefficients. The values ​​of k, A, B, C, D... of surface 6 and surface 7 can be obtained from Table 2-3.

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

[0151]

[0152]

[0153] The coefficients of the even-order aspheric surfaces of surface 6 and surface 7 can be obtained from Table 2-3, and their specific values ​​will not be described one by one in this embodiment.

[0154] See also Fig.10 , Fig.10 : shows a phase distribution diagram of the metalens 20 of the far-infrared optical system 100 provided in Example 2, Fig.10 The horizontal axis represents the distance from the center of the superlens 20. Fig.10 The vertical axis represents the phase. Fig.10It can be seen that the absolute value of the maximum phase difference of the super lens 20 is is 3.41×2πrad. It is worth mentioning that Fig.10 The actual phase distribution of the superlens 20 in Example 2 is given. Since the phase is a periodic function about 2π, there is a relationship: (n is an integer), so it can be based on Fig.10 The phase of the superlens 20 in Example 2 is modulo 2π to achieve normalization processing to meet the needs of actual processing of the superlens 20.

[0155] See also Fig.11 , Fig.11 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at 20° C. is shown. Fig.11 The abscissa in is the image height, and its unit is millimeter; Fig.11 The vertical axis is the MTF value. Fig.11 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig.11 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.42, and the imaging quality of the far-infrared optical system 100 is excellent.

[0156] See also Fig.12 , Fig.12 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at -40°C is shown. Fig.12 The abscissa in is the image height, and its unit is millimeter; Fig.12 The vertical axis is the MTF value. Fig.12 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig.12 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is excellent.

[0157] See also Fig.13 , Fig.13 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at 80° C. is shown. Fig.13 The abscissa in is the image height, and its unit is millimeter; Fig.13The vertical axis is the MTF value. Fig.13 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig.13 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is excellent.

[0158] comprehensive Figures 11 to 13 It can be seen that when the temperature changes within the range of -40°C-80°C, the MTF value changes slightly. Therefore, the far-infrared optical system 100 provided in Example 2 has a good athermalization effect and meets the athermalization requirement.

[0159] See also Fig.14 , Fig.14 FIG. 2 shows a field curvature curve diagram of the far-infrared optical system 100 provided in Example 2. Fig.14 The central horizontal axis is the field curvature, which is in millimeters; Fig.14 The vertical axis is the field of view angle, and its unit is degree. Fig.14 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Fig.14 It can be seen that the field curvature of the far-infrared optical system 100 in the sagittal direction within the full field of view is 0.0415 mm, and the field curvature of the far-infrared optical system 100 in the meridional direction within the full field of view is 0.0754 mm. The field curvature is small, meeting the requirements for field curvature in the excellent imaging quality standard.

[0160] See also Fig.15 , Fig.15 The distortion curves of the far-infrared optical system 100 provided in Example 2 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns are shown. Fig.15 The horizontal axis is distortion, in percentage; Fig.15 The vertical axis is the field of view, and its unit is degree. Fig.15 The distances between the distortion curves of far-infrared light with medium wavelengths of 8 microns, 10 microns, and 12 microns are extremely small, making it difficult to distinguish between the three curves. Therefore, this embodiment does not distinguish between the three curves. Fig.15 It can be seen that the maximum distortion of the far-infrared optical system 100 provided in Example 2 is 0.78%, which is relatively small and meets the requirement of clear imaging.

[0161] See also Fig.16 , Fig.16 The vertical axis chromatic aberration curve of the far-infrared optical system 100 provided in Example 2 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns is shown. Fig.16 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane 70, in millimeters; Fig.16 The vertical axis is the field of view angle, and its unit is degree. Fig.16 There are three curves in total, among which the W2 curve located at 0 microns on the horizontal axis is the far-infrared light with a wavelength of 10 microns, the W1 curve is the far-infrared light with a wavelength of 8 microns, and the W3 curve is the far-infrared light with a wavelength of 12 microns. Fig.16 It can be seen that within the full field of view, the maximum vertical chromatic aberration between different wavelengths is less than 8 microns, the chromatic aberration is small, and the dispersion is not obvious.

[0162] Example 3

[0163] Fig.17 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 3. Fig.17 The mid-to-far infrared optical system 100 includes, in sequence from the object plane 60 to the image plane 70 along the optical axis 80: a first refractive lens 10, an aperture 40, a superlens 20, a second refractive lens 30, and a protective glass 50, wherein the first refractive lens 10 is a spherical lens, and the micro-nano structure 220 is disposed on the object side of the substrate 210.

[0164] Some parameters of the far-infrared optical system 100 provided in Example 3 are shown in Table 3-1.

[0165] Table 3-1. Partial parameters of the far-infrared optical system 100 provided in Example 3

[0166] Optical indicators data Effective focal length 12.95mm F-number 0.9467 Maximum full field of view (H×V×D) 13.51°×10.22°×16.762° Image plane specifications 256×192; 12μm Total optical length (TTL) 19.000mm Optical Back Focus (BFL) 6.093mm Working band Far infrared (8μm-12μm)

[0167] As can be seen from Table 3-1, the working band of the far-infrared optical system 100 is 8μm-12μm, the total optical length of the far-infrared optical system 100 is relatively short, which is 19 mm, and the volume of the far-infrared optical system 100 provided in Example 3 is relatively small. The F number of the far-infrared optical system 100 is 0.9467, and the far-infrared optical system 100 has a large amount of light input.

[0168] Along the direction of the optical axis 80 from the object plane 60 to the image plane 70, starting from the object plane 60, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 3-2.

[0169] Table 3-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 3

[0170] Surface number Optical Components Surface type Curvature radius (mm) Thickness(mm) Material 0 flat unlimited unlimited - 1 First refractive lens Spherical 11.424 4.386 Chalcogenide glass 2 Spherical 12.919 3.172 - 3 Aperture flat unlimited 0.185 - 4 Super Lens Structural surface unlimited 0.300 silicon 5 flat unlimited 1.653 - 6 Second refractive lens even aspherical surface -9.822 3.211 Chalcogenide glass 7 even aspherical surface -8.415 5.493 - 8 Protective glass flat unlimited 0.500 silicon 9 flat unlimited 0.100 - 10 flat unlimited - -

[0171] The analysis of each surface in Table 3-2 can refer to Example 1, and this example does not analyze each surface again.

[0172] Surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0173]

[0174] 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 80; c is the curvature of the aspherical surface, c = 1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 6 and surface 7 can be obtained from Table 3-3.

[0175] Table 3-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 3

[0176] Surface number k A B C D E 6 3.373 -2.643E-4 -1.197E-4 1.101E-5 -4.977E-7 9.001E-9 7 -1.441 -5.136E-4 -1.901E-5 1.278E-6 -4.511E-8 5.238E-10

[0177] The coefficients of the even-order aspheric surfaces of surface 6 and surface 7 can be obtained from Table 3-3, and their specific values ​​will not be described one by one in this embodiment.

[0178] See also Fig.18 , Fig.18 : shows a phase distribution diagram of the super lens 20 of the far-infrared optical system 100 provided in Example 3, Fig.18 The horizontal axis represents the distance from the center of the superlens 20. Fig.18 The vertical axis represents the phase. Fig.18 It can be seen that the absolute value of the maximum phase difference of the super lens 20 is is 3.42×2πrad. It is worth mentioning that Fig.18 The actual phase distribution of the superlens 20 in Example 3 is given. Since the phase is a periodic function about 2π, there is a relationship: (n is an integer), so it can be based on Fig.18 The phase of the superlens 20 in Example 3 is modulo 2π to achieve normalization processing to meet the needs of actual processing of the superlens 20.

[0179] See also Fig.19 , Fig.19 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at 20° C. is shown. Fig.19 The abscissa in is the image height, and its unit is millimeter; Fig.19 The vertical axis is the MTF value. Fig.19 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig.19 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.43, and the imaging quality of the far-infrared optical system 100 is excellent.

[0180] See also Fig. 20 , Fig. 20 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at -40°C is shown. Fig. 20 The abscissa in is the image height, and its unit is millimeter; Fig. 20 The vertical axis is the MTF value. Fig. 20 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig. 20 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.29, and the imaging quality of the far-infrared optical system 100 is excellent.

[0181] See also Fig.21 , Fig.21 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at 80° C. is shown. Fig.21 The abscissa in is the image height, and its unit is millimeter; Fig.21 The vertical axis is the MTF value. Fig.21 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig.21 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is excellent.

[0182] comprehensive Figures 19 to 21 It can be seen that when the temperature changes within the range of -40°C-80°C, the MTF value changes slightly. Therefore, the far-infrared optical system 100 provided in Example 3 has a good athermalization effect and meets the athermalization requirement.

[0183] See also Fig. 22 , Fig. 22 : shows a field curvature curve diagram of the far-infrared optical system 100 provided in Example 3, Fig. 22 The central horizontal axis is the field curvature, which is in millimeters; Fig. 22 The vertical axis is the field of view angle, and its unit is degree. Fig. 22 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Fig. 22 It can be seen that the field curvature of the far-infrared optical system 100 in the sagittal direction within the full field of view is 0.0345 mm, and the field curvature of the far-infrared optical system 100 in the meridional direction within the full field of view is 0.0454 mm. The field curvature is small, meeting the requirements for field curvature in the excellent imaging quality standard.

[0184] See also Fig.23 , Fig.23 The distortion curves of the far-infrared optical system 100 provided in Example 3 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns are shown. Fig.23 The horizontal axis is distortion, in percentage; Fig.23 The vertical axis is the field of view, and its unit is degree. Fig.23 The distances between the distortion curves of far-infrared light with medium wavelengths of 8 microns, 10 microns, and 12 microns are extremely small, making it difficult to distinguish between the three curves. Therefore, this embodiment does not distinguish between the three curves. Fig.23 It can be seen that the maximum distortion of the far-infrared optical system 100 provided in Example 3 is 0.77%, which is relatively small and meets the requirement of clear imaging.

[0185] See also Fig.24 , Fig.24 The vertical axis chromatic aberration curve of the far-infrared optical system 100 provided in Example 3 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns is shown. Fig.24 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane 70, in millimeters; Fig.24 The vertical axis is the field of view angle, and its unit is degree. Fig.24 There are three curves in total, among which the W2 curve located at 0 microns on the horizontal axis is the far-infrared light with a wavelength of 10 microns, the W1 curve is the far-infrared light with a wavelength of 8 microns, and the W3 curve is the far-infrared light with a wavelength of 12 microns. Fig.24 It can be seen that within the full field of view, the maximum vertical chromatic aberration between different wavelengths is less than 5 microns, the chromatic aberration is small, and the dispersion is not obvious.

[0186] Example 4

[0187] Fig.25 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 4. Fig.25 The mid-to-far infrared optical system 100 includes, in sequence from the object plane 60 to the image plane 70 along the optical axis 80: a first refractive lens 10, an aperture 40, a superlens 20, a second refractive lens 30, and a protective glass 50, wherein the first refractive lens 10 is an aspherical lens, and the micro-nano structure 220 is disposed on the object side of the substrate 210.

[0188] Some parameters of the far-infrared optical system 100 provided in Example 4 are shown in Table 4-1.

[0189] Table 4-1. Partial parameters of the far-infrared optical system 100 provided in Example 4

[0190] Optical indicators data focal length 13mm F-number 0.9912 Maximum full field of view (H×V×D) 13.51°×10.22°×16.748° Image plane specifications 256×192; 12μm Total optical length (TTL) 17.608mm Optical Back Focus (BFL) 6.179mm Working band Far infrared (8μm-12μm)

[0191] As can be seen from Table 4-1, the working band of the far-infrared optical system 100 is 8μm-12μm, the total optical length of the far-infrared optical system 100 is relatively short, which is 17.608 mm, and the volume of the far-infrared optical system 100 provided in Example 4 is relatively small. The F number of the far-infrared optical system 100 is 0.9912, and the far-infrared optical system 100 has a large amount of light input.

[0192] Along the direction of the optical axis 80 from the object plane 60 to the image plane 70, starting from the object plane 60, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 4-2.

[0193] Table 4-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 4

[0194]

[0195]

[0196] The analysis of each surface in Table 4-2 can refer to Example 1, and this example does not analyze each surface again.

[0197] Surface 1, surface 2, 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 80; c is the curvature of the aspherical surface, c = 1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of Surface 1, Surface 2, Surface 6 and Surface 7 can be obtained from Table 4-3.

[0200] Table 4-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 4

[0201] Surface number k A B C D E 1 -1.421E-01 -2.567E-05 4.934E-06 -7.737E-08 7.630E-10 -6.242E-12 2 8.078E-01 -1.468E-04 1.863E-05 -5.369E-07 3.421E-09 1.548E-11 6 5.092E+00 3.189E-04 -1.333E-04 4.012E-05 -4.860E-06 3.393E-07 7 -7.960E-01 -8.350E-05 -1.771E-06 6.035E-06 -9.041E-07 6.709E-08

[0202] The coefficients of the even-order aspheric surfaces of surface 1, surface 2, surface 6 and surface 7 can be obtained from Table 4-3, and their specific values ​​will not be described one by one in this embodiment.

[0203] See also Fig.26 , Fig.26 1 shows a phase distribution diagram of the metalens 20 of the far-infrared optical system 100 provided in Example 4, Fig.26 The horizontal axis represents the distance from the center of the superlens 20. Fig.26 The vertical axis represents the phase. Fig.26 It can be seen that the absolute value of the maximum phase difference of the super lens 20 is is 2.83×2πrad. It is worth mentioning that Fig.26 The actual phase distribution of the superlens 20 in Example 4 is given. Since the phase is a periodic function about 2π, there is a relationship: (n is an integer), so it can be based on Fig.26 The phase of the superlens 20 in Example 4 is modulo 2π to achieve normalization processing to meet the needs of actual processing of the superlens 20.

[0204] See also Fig. 27 , Fig. 27 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at 20° C. is shown. Fig. 27 The abscissa in is the image height, and its unit is millimeter; Fig. 27 The vertical axis is the MTF value. Fig. 27 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig. 27 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.39, and the imaging quality of the far-infrared optical system 100 is excellent.

[0205] See also Fig.28 , Fig.28 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at -40°C is shown. Fig.28 The abscissa in is the image height, and its unit is millimeter; Fig.28 The vertical axis is the MTF value. Fig.28 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig.28 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.26, and the imaging quality of the far-infrared optical system 100 is excellent.

[0206] See also Fig.29 , Fig.29 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at 80° C. is shown. Fig.29 The abscissa in is the image height, and its unit is millimeter; Fig.29 The vertical axis is the MTF value. Fig.29 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal curve S2 and the meridional curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal curve S3 and the meridional curve T3 of the field of view. Fig.29 It can be seen that within the full field of view (1.92 mm image height), the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is excellent.

[0207] comprehensive Figure 27 to Figure 29 It can be seen that when the temperature changes within the range of -40°C-80°C, the MTF value changes slightly. Therefore, the far-infrared optical system 100 provided in Example 4 has a good athermalization effect and meets the athermalization requirement.

[0208] See also Fig.30 , Fig.30 FIG. 4 shows a field curvature curve diagram of the far-infrared optical system 100 provided in Example 4. Fig.30 The central horizontal axis is the field curvature, which is in millimeters; Fig.30 The vertical axis is the field of view angle, and its unit is degree. Fig.30S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Fig.30 It can be seen that the field curvature of the far-infrared optical system 100 in the sagittal direction within the full field of view is 0.0600 mm, and the field curvature of the far-infrared optical system 100 in the meridional direction within the full field of view is 0.0767 mm. The field curvature is small and meets the requirements for field curvature in the excellent imaging quality standard.

[0209] See also Fig.31 , Fig.31 The distortion curves of the far-infrared optical system 100 provided in Example 4 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns are shown. Fig.31 The horizontal axis is distortion, in percentage; Fig.31 The vertical axis is the field of view, and its unit is degree. Fig.31 The distances between the distortion curves of far-infrared light with medium wavelengths of 8 microns, 10 microns, and 12 microns are extremely small, making it difficult to distinguish between the three curves. Therefore, this embodiment does not distinguish between the three curves. Fig.31 It can be seen that the maximum distortion of the far-infrared optical system 100 provided in Example 4 is 0.85%, which is relatively small and meets the requirement of clear imaging.

[0210] See also Fig.32 , Fig.32 The vertical axis chromatic aberration curve of the far-infrared optical system 100 provided in Example 4 under far-infrared light with wavelengths of 8 microns, 10 microns, and 12 microns is shown. Fig.32 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane 70, in millimeters; Fig.32 The vertical axis is the field of view angle, and its unit is degree. Fig.32 There are three curves in total, among which the W2 curve located at 0 microns on the horizontal axis is the far-infrared light with a wavelength of 10 microns, the W1 curve is the far-infrared light with a wavelength of 8 microns, and the W3 curve is the far-infrared light with a wavelength of 12 microns. Fig.32 It can be seen that within the full field of view, the maximum vertical chromatic aberration between different wavelengths is less than 4 microns, the chromatic aberration is small, and the dispersion is not obvious.

[0211] After summarizing the various parameters of the far-infrared optical system 100 provided by the above four embodiments, the following Table 5 is obtained. Table 5 is mainly used to illustrate that the various conditions satisfied by the far-infrared optical system 100 provided by the present application are all verified and supported by experiments.

[0212] Table 5. Parameters of the far-infrared optical system 100 provided in various embodiments

[0213]

[0214]

[0215] The present application also provides a far-infrared optical lens, which includes an imaging detector (not shown) and the above-mentioned far-infrared optical system 100. The specific structure of the far-infrared optical system 100 can be found above and will not be repeated here. The imaging detector is arranged on the image plane 70 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).

[0216] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the invention 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 comprises, in order from the object side to the image side along the optical axis: a first refractive lens, a super lens, and a second refractive lens; the first refractive lens has a positive focal power, the object side surface of the first refractive lens is convex to the object side, and the image side surface of the first refractive lens is convex to the object side; the super lens has a positive focal power; the second refractive lens is an aspherical lens, the second refractive lens has a positive focal power, the object side surface of the second refractive lens is convex to the image side, and the image side surface of the second refractive lens is convex to the image side; The far-infrared optical system meets the following requirements: Among them, the is the maximum phase difference of the superlens.

2. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the is the phase of the metalens, r is the radius of the metalens, FNO is the aperture number of the far-infrared optical system, and D meta is the maximum effective diameter of the metalens, and the BFL is the optical back focus of the far-infrared optical system.

3. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the SAG 31 is the sag height of the object side surface of the second refractive lens, the SAG 32 is the sagittal height of the image side surface of the second refractive lens, and f3 is the focal length of the second refractive lens.

4. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the FOV is the maximum field angle of the far-infrared optical system, the D1 is the maximum effective diameter of the object side of the first refractive lens, and the EPD is the entrance pupil diameter of the far-infrared optical system.

5. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the R 11 is the radius of curvature of the object side surface of the first refractive lens, and the R 12 is the curvature radius of the image-side surface of the first refractive lens, and f1 is the focal length of the first refractive lens.

6. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, f1 is the focal length of the first refractive lens, f3 is the focal length of the second refractive lens, and SAG 11 is the sag height of the object side surface of the first refractive lens, the SAG 12 is the sagittal height of the image side surface of the first refractive lens, the SAG 31 is the sag height of the object side surface of the second refractive lens, the SAG 32 is the sagittal height of the image-side surface of the second refractive lens.

7. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the TTL is the total optical length of the far-infrared optical system, the FNO is the aperture number of the far-infrared optical system, the D1 is the maximum effective diameter of the object side of the first refractive lens, the EPD is the entrance pupil diameter of the far-infrared optical system, and the n1 is the refractive index of the first refractive lens.

8. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: The BFL is the optical back focus of the far-infrared optical system, and the SAG 32 is the sagittal height of the image side surface of the second refractive lens, and CT3 is the central thickness of the second refractive lens.

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

10. A far-infrared optical lens, characterized in that: The far-infrared optical lens comprises: an imaging detector and a far-infrared optical system as described in any one of claims 1 to 9; the imaging detector is arranged on the image plane of the far-infrared optical system.

Images