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 aspheric lens, a second aspheric lens, a super lens and a third aspheric lens from an object side to an image side along an optical axis, the focal power of the first aspheric lens is positive, and the object side surface and the image side surface of the first aspheric lens both protrude towards the object side; the object side surface and the image side surface of the second aspheric lens are convex towards the object side; the focal power of the super lens is positive; the focal power of the third aspheric lens is positive, and the object side face of the third aspheric lens protrudes towards the object side. The far infrared optical system provided by the invention has the advantages of excellent imaging quality, small size and low cost. Moreover, the far-infrared optical system comprises the super lens, and the production cost of the super lens is low, so that the production cost of the far-infrared optical system can be further reduced. In addition, the far infrared optical system provided by the invention also has a good athermalization effect.

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] With the development of science and technology, far-infrared optical systems are widely used in many fields. In the prior art, far-infrared optical systems usually use multiple lenses, which leads to the problem of large volume of far-infrared optical systems. In order to improve the imaging quality, the lenses of far-infrared optical systems include multiple aspherical lenses, and the material of some lenses is germanium, which is relatively expensive, resulting in high production costs of far-infrared optical systems. Moreover, some far-infrared optical systems have poor adaptability to temperature changes, resulting in their imaging quality being greatly affected by temperature, making their application range small. Summary of the invention

[0003] In view of 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 at least one disadvantage of the far-infrared optical system in the prior art.

[0004] 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 first aspheric lens, a second aspheric lens, a super lens and a third aspheric lens; the optical focal length of the first aspheric lens is positive, the object side surface of the first aspheric lens is convex toward the object side, and the image side surface of the first aspheric lens is convex toward the object side; the object side surface of the second aspheric lens is convex toward the object side, and the image side surface of the second aspheric lens is convex toward the object side; the optical focal length of the super lens is positive; the optical focal length of the third aspheric lens is positive, and the object side surface of the third aspheric lens is convex toward the object side.

[0005] In some embodiments, the far-infrared optical system satisfies:

[0006]

[0007] Among them, the f m is the focal length of the superlens, and the f gm1 is the focal length of the first aspheric lens, and the f gm2 is the focal length of the second aspheric lens, the f gm3 is the focal length of the third aspheric lens, and L1 is the distance between the object side surface of the first aspheric lens and the object side surface of the second aspheric lens on the optical axis.

[0008] In some embodiments, the far-infrared optical system satisfies: Among them, the θ maxis the absolute value of the maximum phase difference of the metalens, and the f m is the focal length of the metalens, and D m is the effective diameter of the superlens.

[0009] In some embodiments, the far-infrared optical system satisfies: Wherein, L2 is the distance between the object side surface of the super lens and the object side surface of the first aspheric lens on the optical axis, and D m is the effective diameter of the superlens.

[0010] In some embodiments, the far-infrared optical system satisfies: Wherein, f is the effective focal length of the far-infrared optical system, and f gm1 is the focal length of the first aspheric lens, and the f m is the focal length of the superlens, and the f gm3 is the focal length of the third aspheric lens.

[0011] In some embodiments, the far-infrared optical system satisfies: Among them, the R 1gm1 is the radius of curvature of the object side of the first aspheric lens, and the R 2gm1 is the radius of curvature of the image side surface of the first aspheric lens, and the R 1gm2 is the radius of curvature of the object side of the second aspheric lens, and the R 2gm2 is the radius of curvature of the image-side surface of the second aspheric lens.

[0012] 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 FOV is the maximum field of view angle of the far-infrared optical system, f is the effective focal length of the far-infrared optical system, and the BFL is the optical back focus of the far-infrared optical system.

[0013] In some embodiments, the far-infrared optical system satisfies: Wherein, BFL is the optical back focus of the far-infrared optical system, f is the effective focal length of the far-infrared optical system, and f gm1 is the focal length of the first aspheric lens, and the f gm3 is the focal length of the third aspheric lens.

[0014] In some embodiments, the far-infrared optical system satisfies: Among them, the D mis the effective diameter of the metalens, the FNO is the aperture number of the far-infrared optical system, and f is the effective focal length of the far-infrared optical system.

[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 aspheric 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 includes: a first aspheric lens, a second aspheric lens, a super lens and a third aspheric lens in sequence from the object side to the image side along the optical axis; the optical power of the first aspheric lens is positive, the object side surface of the first aspheric lens is convex to the object side, and the image side surface of the first aspheric lens is convex to the object side; the object side surface of the second aspheric lens is convex to the object side, and the image side surface of the second aspheric lens is convex to the object side; the optical power of the super lens is positive; the optical power of the third aspheric lens is positive, and the object side surface of the third aspheric lens is convex to the object side. The imaging quality of the far-infrared optical system provided by the present application is excellent. Since the number of lenses of the far-infrared optical system is relatively small, the far-infrared optical system has the advantages of small size and low cost. In addition, the far-infrared optical system includes a super lens, and the production cost of the super lens is low, which can further reduce the production cost of the far-infrared optical system. In addition, the imaging quality of the far-infrared optical system provided by the present application is less affected by temperature changes, and has a good athermal effect, so that the far-infrared optical system has a wide range of applications. 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 superlens in 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 schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0025] Figure 7 The phase distribution diagram of the superlens in the far-infrared optical system in one embodiment of the present application is shown.

[0026] Figure 8 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0027] Fig. 9 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0028] Fig.10 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0029] Fig.11 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0030] Fig.12 The phase distribution diagram of the superlens in the far-infrared optical system 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 20° C. in one embodiment of the present application is shown.

[0032] Fig.14 The MTF field of view curve of the far-infrared optical system at -40°C in one embodiment of the present application is shown.

[0033] Fig.15 The MTF field of view curve of the far-infrared optical system at 80° C. in one embodiment of the present application is shown.

[0034] Fig.16 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0035] Fig.17 The phase distribution diagram of the superlens in the far-infrared optical system in one embodiment of the present application is shown.

[0036] Fig.18 The MTF field of view curve of the far-infrared optical system at 20° C. in one embodiment of the present application is shown.

[0037] Fig.19 The MTF field of view curve of the far-infrared optical system at -40°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 80° C. in one embodiment of the present application is shown.

[0039] Reference numerals

[0040] 100. Far-infrared optical system; 10. First aspheric lens; 20. Second aspheric lens; 30. Super lens; 310. Substrate; 320. Micro-nano structure; 40. Third aspheric lens; 50. Aperture; 60. Protective glass; A. Object plane; B. Image plane; S. Optical axis. DETAILED DESCRIPTION

[0041] 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.

[0042] 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.

[0043] 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 1 In the figure, the object is located on the left side of the leftmost lens, that is, the object side is located on the left side of the leftmost lens, and the object plane A is located on the object side. The image formed by the far-infrared optical system 100 is located on the right side of the rightmost lens, that is, the image side is located on the right side of the rightmost lens, and the image plane B is located on the image side. Therefore, the direction from the object plane A to the image plane B along the optical axis S is consistent with the direction from the object side to the image side along the optical axis S.

[0044] 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. For example, the side of the diaphragm 50 close to the object side is the object side of the diaphragm 50. 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. For example, the surface of the diaphragm 50 close to the image side is the image side surface of the diaphragm 50.

[0045] The far-infrared optical system 100 includes a first aspheric lens 10, a second aspheric lens 20, a super lens 30 and a third aspheric lens 40, which are arranged in sequence from the object side to the image side along the optical axis S.

[0046] The first aspheric lens 10 has a positive refractive power, an object-side surface of the first aspheric lens 10 is convex toward the object side, and an image-side surface of the first aspheric lens 10 is convex toward the object side.

[0047] The optical power of the second aspheric lens 20 can be positive or negative, that is, in some embodiments, the optical power of the second aspheric lens 20 is positive; in some embodiments, the optical power of the second aspheric lens 20 is negative. The object side surface of the second aspheric lens 20 is convex to the object side, and the image side surface of the second aspheric lens 20 is convex to the object side.

[0048] The optical power of the superlens 30 is positive, and the superlens 30 includes a substrate 310 and a micro-nano structure 320. The micro-nano structure 320 is a sub-wavelength structure, and the micro-nano structure 320 is arranged on the object side of the substrate 310 and / or the image side of the substrate 310. According to the phase modulation method adopted, the corresponding phase modulation formula can be adaptively used to configure various parameters of the micro-nano structure 320, so that the superlens 30 has the expected optical performance.

[0049] The third aspheric lens 40 has positive refractive power, and the object-side surface of the third aspheric lens 40 is convex toward the object side.

[0050] The imaging quality of the far-infrared optical system 100 provided by the present application is excellent. Since the number of lenses of the far-infrared optical system 100 is relatively small, the far-infrared optical system 100 has the advantages of small size and low cost. In addition, the far-infrared optical system 100 includes a super lens 30, and the production cost of the super lens 30 is low, which can further reduce the production cost of the far-infrared optical system 100. In addition, the imaging quality of the far-infrared optical system 100 provided by the present application is less affected by temperature changes, and has a good athermal effect, so that the far-infrared optical system 100 has a wide range of applications.

[0051] Compared with the traditional far-infrared optical system in the prior art, the far-infrared optical system 100 provided in the present application includes a superlens 30. The production cost of the superlens 30 is relatively low, and the superlens 30 can introduce negative dispersion. When combined with the first aspheric lens 10, the second aspheric lens 20, and the third aspheric lens 40, the chromatic aberration of the far-infrared optical system 100 can be effectively reduced, and the production cost of the far-infrared optical system 100 can be reduced while improving the imaging quality of the far-infrared optical system 100.

[0052] In some embodiments, the paraxial region of the image-side surface of the third aspheric lens 40 is convex toward the image side, wherein the “paraxial region” in the present application refers to a region of the lens surface close to the optical axis S.

[0053] For the superlens 30, this article does not limit its specific structure. Specifically, the side of the substrate 310 on which the micro-nano structure 320 is set, the positive and negative of the micro-nano structure 320, the number of layers of the micro-nano structure 320, etc. can be freely combined, as long as the superlens 30 has the expected performance. It should be noted that the superlens 30 modulates the light by providing a phase. According to the principle of phase superposition, a phase consistent with the expectation can be provided by a superlens 30, or by two or more superlenses 30. Therefore, the number of superlenses 30 in the far-infrared optical system 100 provided in this application is not limited, and it can be one, two or more.

[0054] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 1:

[0055]

[0056] Among them, f m is the focal length of the metalens, f gm1 is the focal length of the first aspheric lens 10, f gm2 is the focal length of the second aspherical lens 20, f gm3 is the focal length of the third aspheric lens, and L1 is the distance between the object side surface of the first aspheric lens 10 and the object side surface of the second aspheric lens 20 on the optical axis S. m 、f gm1 、f gm2 、f gm3 , L1 have the same dimension, both are length units, such as millimeters.

[0057] Conditional formula 1 indicates that the focal lengths of the first aspheric lens 10 and the third aspheric lens 40 are both positive, and the third aspheric lens 40 provides a larger optical power in the far-infrared optical system 100. The upper and lower limits of conditional formula 1 can ensure that the third aspheric lens 40 has a focusing function, and reduce the optical power of the super lens 30, so as to ensure that the super lens 30 provides negative dispersion in the far-infrared optical system 100.

[0058] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 2: Among them, θ max is the absolute value of the maximum phase difference of the super lens 30, θ max The unit of f is 2πrad. m is the focal length of the superlens 30, D m is the effective diameter of the superlens 30, which is the diameter of the maximum light-transmitting area of ​​the superlens 30, and the same applies below. m , D m have the same dimension, which is a unit of length, such as millimeter.

[0059] Conditional expression 2 indicates that the metalens 30 of a specific numerical aperture has a suitable optical focal length in the far-infrared optical system 100, and the upper and lower limits of conditional expression 2 are used to ensure that the refractive power corresponding to the phase distribution of the metalens 30 of a specific numerical aperture within the full aperture reaches the best effect.

[0060] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 3: Wherein, L2 is the distance between the object side surface of the super lens 30 and the object side surface of the first aspheric lens 10 on the optical axis S, and D m is the effective diameter of the super lens 30. L2, D m have the same dimension, which is a unit of length, such as millimeter.

[0061] In the present application, the far-infrared optical system 100 in which the ratio of the distance between the object side surface of the metalens 30 and the object side surface of the first aspheric lens 10 on the optical axis S (i.e., L2) to the total optical length of the far-infrared optical system 100 is a constant is called a specific ratio optical system, and the specific ratio optical system has a specific ratio optical total length, the same below. Conditional formula three indicates that the metalens 30, the first aspheric lens 10, and the second aspheric lens 20 form a lens group, ensuring that the metalens 30 has a suitable placement position under the specific ratio optical total length, and the size of the metalens 30 can also meet the assembly requirements.

[0062] In some embodiments, the far-infrared optical system 100 satisfies Condition 4: Wherein, f is the effective focal length of the far-infrared optical system 100, and f gm1 is the focal length of the first aspheric lens 10, fm is the focal length of the superlens 30, f gm3 is the focal length of the third aspherical lens 40. f, f gm1 、f m 、f gm3 have the same dimension, which is a unit of length, such as millimeter.

[0063] Conditional expression 4 reflects the relationship between the focal lengths of the lenses in the far-infrared optical system 100 , so that the optical power of the far-infrared optical system 100 can be reasonably distributed, which is beneficial to correcting the aberration of the far-infrared optical system 100 and reducing the optical sensitivity of the far-infrared optical system 100 .

[0064] In some embodiments, the far-infrared optical system 100 satisfies Condition 5: Among them, R 1gm1 is the radius of curvature of the object side surface of the first aspheric lens 10, R 2gm1 is the curvature radius of the image side surface of the first aspheric lens 10, R 1gm2 is the radius of curvature of the object side surface of the second aspheric lens 20, R 2gm2 R is the curvature radius of the image side surface of the second aspherical lens 20. 1gm1 , R 2gm1 , R 1gm2 , R 2gm2 have the same dimension, which is a unit of length, such as millimeter.

[0065] Conditional expression 5 indicates that the first aspheric lens 10 and the second aspheric lens 20 form a lens group. Conditional expression 5 can ensure that under a specific ratio of the total optical length, the first aspheric lens 10 and the second aspheric lens 20 can better correct high-order aberrations.

[0066] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 6: Wherein, TTL (Total Track Length, referred to as TTL) is the total optical length of the far-infrared optical system 100, FOV is the maximum field angle of the far-infrared optical system 100, and its unit is degree. f is the effective focal length of the far-infrared optical system 100, and BFL (Back focal length, referred to as BFL) is the optical back focal length of the far-infrared optical system 100. In the present application, BFL is the distance between the image side surface of the third aspheric lens 40 and the image surface B on the optical axis S, and the same below. TTL, f, and BFL have the same dimension, which are all length units, such as millimeters.

[0067] The lower limit of conditional expression 6 indicates that the far-infrared optical system 100 can achieve clear imaging while having a smaller total optical length, so that the far-infrared optical system 100 has both excellent imaging quality and a smaller volume. The upper limit of conditional expression 6 can ensure that the far-infrared optical system 100 has sufficient optical back focus, which can facilitate the assembly of the far-infrared optical system 100.

[0068] In some embodiments, the far-infrared optical system 100 satisfies conditional equation 7: Wherein, BFL is the optical back focus of the far-infrared optical system 100, f is the effective focal length of the far-infrared optical system 100, and f gm1 is the focal length of the first aspheric lens 10, f gm3 is the focal length of the third aspherical lens 40. BFL, f, f gm1 、f gm3 have the same dimension, which is a unit of length, such as millimeter.

[0069] The lower limit of conditional expression 7 reflects the minimum optical back focus length that can be achieved when the far-infrared optical system 100 meets the imaging performance, and the upper limit of conditional expression 7 reflects the maximum optical back focus length that can be achieved when the far-infrared optical system 100 meets the imaging performance. Conditional expression 7 reflects the range of the optical back focus when the far-infrared optical system 100 meets the imaging performance. Since the length of the optical back focus affects the size of the total optical length, and the size of the total optical length affects the volume of the far-infrared optical system 100, the length of the optical back focus can be reasonably controlled under the premise of meeting the imaging performance, so that the far-infrared optical system 100 can have a smaller volume and be easy to assemble.

[0070] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 8: Among them, D m is the effective diameter of the super lens 30, 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, and f is the effective focal length of the far-infrared optical system 100. m , f have the same dimension, both are length units, such as millimeters.

[0071] Conditional formula eight ensures that under a specific ratio of the total optical length, the metalens 30 is located at the position with the smallest aperture in the far-infrared optical system, thereby effectively and reasonably modulating the intersecting light rays of each field of view. Compared with the metalens in the far-infrared optical system in the prior art, the metalens 30 of the far-infrared optical system 100 provided in the present application has a smaller aperture. Since the metalens 30 is obtained based on the processing of the whole wafer, when the wafer size is fixed (for example, a 4-inch wafer, a 6-inch wafer, an 8-inch wafer or a 12-inch wafer), the smaller the aperture of a single metalens 30, the more metalens 30 can be processed from a single wafer, and the lower the cost of a single metalens 30. Therefore, the production cost of the metalens 30 in the far-infrared optical system 100 provided in the present application can be further reduced, which is conducive to compressing the production cost of the far-infrared optical system 100.

[0072] In some embodiments, the far-infrared optical system 100 further includes an aperture 50, which is used to control 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.

[0073] In some embodiments, the aperture 50 is disposed on the object side of the first aspheric lens 10. Specifically, the aperture 50 may be disposed at any of the following positions:

[0074] (1) The aperture 50 is disposed on the object side of the first aspheric lens 10, and the aperture 50 is spaced apart from the first aspheric lens 10;

[0075] (2) The aperture 50 is disposed on the object side of the first aspheric lens 10 , and the aperture 50 is disposed in contact with the object side surface of the first aspheric lens 10 , that is, the aperture 50 is disposed on the object side surface of the first aspheric lens 10 .

[0076] In some embodiments, the aperture 50 is disposed between any two adjacent lenses. Specifically, the aperture 50 may be disposed at any of the following positions:

[0077] (1) The aperture 50 is located between the first aspheric lens 10 and the second aspheric lens 20, and the aperture 50 is attached to the image side surface of the first aspheric lens 10;

[0078] (2) The aperture 50 is located between the first aspheric lens 10 and the second aspheric lens 20, and the aperture 50 is spaced apart from the first aspheric lens 10 and the second aspheric lens 20;

[0079] (3) The aperture 50 is located between the first aspheric lens 10 and the second aspheric lens 20, and the aperture 50 is attached to the object side surface of the second aspheric lens 20;

[0080] (4) The aperture 50 is located between the second aspheric lens 20 and the super lens 30, and the aperture 50 is attached to the image side surface of the second aspheric lens 20;

[0081] (5) The aperture 50 is located between the second aspheric lens 20 and the super lens 30, and the aperture 50 is spaced apart from the second aspheric lens 20 and the super lens 30;

[0082] (6) The aperture 50 is located between the second aspheric lens 20 and the super lens 30, and the aperture 50 is arranged in contact with the object side surface of the super lens 30;

[0083] (7) The aperture 50 is located between the super lens 30 and the third aspheric lens 40, and the aperture 50 is arranged in contact with the image side surface of the super lens 30;

[0084] (8) The aperture 50 is located between the super lens 30 and the third aspheric lens 40, and the aperture 50 is spaced apart from the super lens 30 and the third aspheric lens 40;

[0085] (9) The aperture 50 is located between the super lens 30 and the third aspheric lens 40 , and the aperture 50 is attached to the object side surface of the third aspheric lens 40 .

[0086] Furthermore, in some embodiments, the aperture 50 is disposed on the object side of the first aspheric lens 10, or the aperture 50 is disposed between the first aspheric lens 10 and the second aspheric lens 20, which can limit the light whose edge field aberration is difficult to correct from entering the far-infrared optical system 100, which is beneficial to improving the imaging quality of the far-infrared optical system. Among them, compared with the aperture 50 being disposed between the first aspheric lens 10 and the second aspheric lens 20, when the aperture 50 is disposed on the object side of the first aspheric lens 10, the aperture of the first aspheric lens 10 is smaller, which can make the far-infrared optical system 100 have a smaller aperture at the end close to the object side, and can make the exposed volume of the far-infrared optical system 100 smaller (when in use, the end close to the image side of the far-infrared optical system 100 is usually accommodated in the external structural member, and the end close to the object side of the far-infrared optical system 100 is exposed), which is beneficial to improving the concealment of the far-infrared optical system 100.

[0087] In some embodiments, the far-infrared optical system 100 further includes a protective glass 60, which is located between the third aspherical lens 40 and the image plane B. The protective glass 60 is used to protect an imaging detector matched with the far-infrared optical system 100 to reduce the probability of damage to the far-infrared optical system 100. The present application does not limit the material of the protective glass 60, and illustratively, the material of the protective glass 60 is silicon or germanium.

[0088] The far-infrared optical system 100 provided by the present application has the following benefits:

[0089] (1) F number ≤ 1.0;

[0090] (2) At 20°C, the MTF (Modulation Transfer Function, MTF for short) of all viewing fields within a half viewing angle of 23° at 42lp / mm is greater than 0.24;

[0091] (3) Total optical length (TTL) < 36 mm;

[0092] (4) The diameter of the superlens 30 is small and the cost is low.

[0093] 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.

[0094] Example 1

[0095] 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-to-far infrared optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, in sequence: an aperture 50, a first aspheric lens 10, a second aspheric lens 20, a super lens 30, a third aspheric lens 40, and a protective glass 60, wherein the micro-nano structure 320 is disposed on the object side of the substrate 310 (the size of the micro-nano structure is relatively small, and is limited by the size of the picture, resulting in the specific position of the micro-nano structure in the figure being difficult to clearly display, and the same is true for the schematic diagrams of the architecture layout of other embodiments). Some parameters of the far-infrared optical system 100 provided in Example 1 are shown in Table 1-1.

[0096] Table 1-1. Partial parameters of the far-infrared optical system 100 provided in Example 1

[0097] parameter data Total optical length (TTL) 34.41mm Maximum field of view (2ω) 46° F-number 1.0 Effective focal length 24mm Working band Far infrared light (10±2μm)

[0098] As can be seen from Table 1-1, the working band of the far-infrared optical system 100 is 8 μm-12 μm, and the total optical length of the far-infrared optical system 100 is relatively short, only 34.41 mm, so 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 1.0, which can ensure that the far-infrared optical system 100 has a large amount of light entering.

[0099] Along the optical axis S from the object plane A to the image plane B, starting from the aperture 50, 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.

[0100] Table 1-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 1

[0101] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aperture unlimited -4.09 - 2 Aspheric 23.12 4.47 Chalcogenide glass 3 Aspheric 31.22 0.37 - 4 Aspheric 15.19 3.47 Chalcogenide glass 5 Aspheric 8.5 4.68 - 6 Structural surface unlimited 0.33 silicon 7 Spherical unlimited 6 - 8 Aspheric 58.62 6.13 Chalcogenide glass 9 Aspheric -89.29 5 - 10 Spherical unlimited 0.77 silicon 11 Spherical unlimited 3.19 -

[0102] For each surface in Table 1-2, surface 1 is the aperture 50, surface 2 is the object side surface of the first aspheric lens 10, and surface 3 is the image side surface of the first aspheric lens 10. Surface 4 is the object side surface of the second aspheric lens 20, and surface 5 is the image side surface of the second aspheric lens 20. Surface 6 is the object side surface of the super lens 30. Since the micro-nano structure 320 is provided on surface 6, surface 6 is recorded as the structural surface, and surface 7 is the image side surface of the super lens 30. Surface 8 is the object side surface of the third aspheric lens 40, and surface 9 is the image side surface of the third aspheric lens 40. Surface 10 is the object side surface of the protective glass 60, and surface 10 is the image side surface of the protective glass 60.

[0103] As can be seen from Table 1-2, the radius of curvature of surface 1 is infinite, that is, surface 1 is a plane, and the distance between surface 1 and surface 2 is -4.09 mm, where the negative sign in "-4.09" means that the vertex of surface 2 is convex from surface 1 toward the object side. Surface 2 is an aspherical surface, the radius of curvature of surface 2 is 23.12 mm, the distance between surface 2 and surface 3 is 4.47 mm, and the material between surface 2 and surface 3 is chalcogenide glass. Surface 3 is an aspherical surface, the curvature of surface 3 is 31.22 mm, the distance between surface 3 and surface 4 is 0.37 mm, and the material between surface 3 and surface 4 is air. Surface 4 is an aspherical surface, the radius of curvature of surface 4 is 15.19 mm, the distance between surface 4 and surface 5 is 3.47 mm, and the material between surface 4 and surface 5 is chalcogenide glass. Surface 5 is an aspherical surface, the radius of curvature of surface 5 is 8.5 mm, the distance between surface 5 and surface 6 is 4.68 mm, and the material between surface 5 and surface 6 is air. The radius of curvature of surface 6 is infinite, that is, surface 6 is a plane, the distance between surface 6 and surface 7 is 0.33 mm, and the material between surface 6 and surface 7 is silicon. Surface 7 is a spherical surface, the radius of curvature of surface 7 is infinite, that is, surface 7 is a plane, the distance between surface 7 and surface 8 is 6 mm, and the material between surface 7 and surface 8 is air. Surface 8 is an aspherical surface, the radius of curvature of surface 8 is 58.62 mm, the distance between surface 8 and surface 9 is 6.13 mm, and the material between surface 8 and surface 9 is chalcogenide glass. Surface 9 is an aspherical surface, the radius of curvature of surface 9 is -89.29 mm, the distance between surface 9 and surface 10 is 5 mm, and the material between surface 9 and surface 10 is air. Surface 10 is a spherical surface, the radius of curvature of surface 10 is infinite, that is, surface 10 is a plane, the distance between surface 10 and surface 11 is 0.77 mm, and the material between surface 10 and surface 11 is silicon. The surface 11 is a spherical surface, and the curvature radius of the surface 11 is infinite, that is, the surface 11 is a plane, the distance between the surface 11 and the image plane B is 3.19 mm, and the material between the surface 11 and the image plane B is air.

[0104] Surface 2, surface 3, surface 4, surface 5, surface 8 and surface 9 are all even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0105]

[0106] 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... of surface 2, surface 3, surface 4, surface 5, surface 8 and surface 9 can be obtained from Table 1-3.

[0107] Table 1-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 1

[0108]

[0109] Please refer to Table 1-3. For surface 2, k is -9.76E-02, A is -1.54E-06, B is 7.92E-08, C is 1.72E-09, D is -3.50E-11, E is 2.09E-13, F is -5.94E-16, and G is 1.18E-18. The coefficients of the even-order aspheric surfaces of surface 3, surface 4, surface 5, surface 8, and surface 9 can be obtained from Table 1-3 with reference to surface 2, and will not be elaborated here one by one.

[0110] Figure 2 This is a phase distribution diagram of the superlens 30 of the far-infrared optical system 100 provided in Example 1 at a main wavelength of 10 microns, wherein the horizontal axis is a coordinate axis established with the center of the superlens 30 as the origin.

[0111] See also Figure 3 , Figure 3 The MTF field curve of the far-infrared optical system 100 provided in Example 1 at 20° C. is shown. Figure 3 The horizontal axis in is the Y-axis field of view, and its unit is degree; Figure 3 The vertical axis is the MTF value. Figure 3 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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 entire field of view, the MTF is greater than 0.28, and the imaging quality of the far-infrared optical system 100 is excellent.

[0112] 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 horizontal axis in is the Y-axis field of view, and its unit is degree; Figure 4 The vertical axis is the MTF value. Figure 4 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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 entire field of view, the MTF is greater than 0.29, and the imaging quality of the far-infrared optical system 100 is excellent.

[0113] 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 horizontal axis in is the Y-axis field of view, and its unit is degree; Figure 5 The vertical axis is the MTF value. Figure 5 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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 entire field of view, the MTF is greater than 0.2, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0114] comprehensive Figures 3 to 5 It can be seen that when the temperature changes within the range of -40°C-80°C, the MTF of the far-infrared optical system 100 provided in Example 1 is less affected by the temperature change. Therefore, the far-infrared optical system 100 provided in Example 1 has an excellent athermal effect within the range of -40°C-80°C.

[0115] Example 2

[0116] Figure 6 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 2. Figure 6 The mid-infrared optical system 100 includes, along the optical axis S from the object plane A to the image plane B, an aperture 50, a first aspheric lens 10, a second aspheric lens 20, a super lens 30, a third aspheric lens 40, and a protective glass 60, wherein the micro-nano structure 320 is disposed on the object side of the substrate 310. Some parameters of the far-infrared optical system 100 provided in Example 2 are shown in Table 2-1.

[0117] Table 2-1. Partial parameters of the far-infrared optical system 100 provided in Example 2

[0118] parameter data Total optical length (TTL) 35.16mm Maximum field of view (2ω) 46° F-number 1.0 Effective focal length 24mm Working band Far infrared light (10±2μm)

[0119] As can be seen from Table 2-1, the working band of the far-infrared optical system 100 is 8 μm-12 μm, and the total optical length of the far-infrared optical system 100 is relatively short, only 35.16 mm, so 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 1.0, which can ensure that the far-infrared optical system 100 has a large amount of light entering.

[0120] Along the optical axis S from the object plane A to the image plane B, starting from the aperture 50, 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.

[0121] Table 2-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 2

[0122]

[0123]

[0124] The analysis of each surface in Table 2-2 can refer to Example 1, and no analysis is performed again in this example.

[0125] Surface 2, surface 3, surface 4, surface 5, surface 8 and surface 9 are all even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0126]

[0127] 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 radius of curvature of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of Surface 2, Surface 3, Surface 4, Surface 5, Surface 8 and Surface 9 can be obtained from Table 2-3.

[0128] Table 2-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 2

[0129] Surface serial number k A B C D E F G 2 -1.67E-01 -5.04E-06 1.18E-07 1.81E-09 -3.58E-11 2.20E-13 -6.28E-16 4.77E-19 3 5.48E+00 2.32E-05 4.76E-07 -1.62E-08 1.27E-10 -4.49E-13 5.43E-16 -1.22E-19 4 4.04E-01 -2.71E-06 3.02E-07 -1.69E-08 -7.11E-11 6.80E-13 1.18E-14 -8.31E-17 5 -4.78E-01 1.57E-06 1.93E-06 -5.24E-08 -3.64E-10 5.87E-12 1.11E-13 -1.16E-15 8 7.76E+00 1.91E-05 -1.38E-07 2.39E-10 6.43E-12 -8.30E-14 3.65E-16 -5.22E-19 9 -9.85E+01 5.96E-06 -1.25E-07 1.81E-09 -1.76E-11 8.37E-14 -2.01E-16 2.56E-19

[0130] The even-order aspheric coefficients of surface 2, surface 3, surface 4, surface 5, surface 8 and surface 9 can be obtained from Table 2-3 and will not be elaborated here one by one.

[0131] Figure 7 This is a phase distribution diagram of the superlens 30 of the far-infrared optical system 100 provided in Example 2 at a main wavelength of 10 microns, wherein the horizontal axis is a coordinate axis established with the center of the superlens 30 as the origin.

[0132] See also Figure 8 , Figure 8 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at 20° C. is shown. Figure 8 The horizontal axis in is the Y-axis field of view, and its unit is degree; Figure 8 The vertical axis is the MTF value. Figure 8The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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 8 It can be seen that within the entire field of view, the MTF is greater than 0.28, and the imaging quality of the far-infrared optical system 100 is excellent.

[0133] See also Fig. 9 , Fig. 9 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at -40°C is shown. Fig. 9 The horizontal axis in is the Y-axis field of view, and its unit is degree; Fig. 9 The vertical axis is the MTF value. Fig. 9 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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. 9 It can be seen that within the entire field of view, the MTF is greater than 0.24, and the imaging quality of the far-infrared optical system 100 is excellent.

[0134] See also Fig.10 , Fig.10 The MTF field curve of the far-infrared optical system 100 provided in Example 2 at 80° C. is shown. Fig.10 The horizontal axis in is the Y-axis field of view, and its unit is degree; Fig.10 The vertical axis is the MTF value. Fig.10 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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.10 It can be seen that within the entire field of view, the MTF is greater than 0.1, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0135] comprehensive Figures 8 to 10 It can be seen that when the temperature changes within the range of -40°C-80°C, the MTF of the far-infrared optical system 100 provided in Example 2 is less affected by the temperature change, that is, the far-infrared optical system 100 provided in Example 2 has a good athermal effect within the range of -40°C-80°C.

[0136] Example 3

[0137] Fig.11 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 3. Fig.11 The mid-infrared optical system 100 includes, along the optical axis S, from the object plane A to the image plane B: a first aspheric lens 10, an aperture 50, a second aspheric lens 20, a super lens 30, a third aspheric lens 40, and a protective glass 60, wherein the micro-nano structure 320 is disposed on the object side of the substrate 310. Some parameters of the far-infrared optical system 100 provided in Example 3 are shown in Table 3-1.

[0138] Table 3-1. Partial parameters of the far-infrared optical system 100 provided in Example 3

[0139]

[0140]

[0141] As can be seen from Table 3-1, the working band of the far-infrared optical system 100 is 8 μm-12 μm, and the total optical length of the far-infrared optical system 100 is relatively short, only 35.15 mm, so 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 1.0, which can ensure that the far-infrared optical system 100 has a large amount of light entering.

[0142] Along the optical axis S from the object plane A to the image plane B, starting from the first aspheric lens 10, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 3-2.

[0143] Table 3-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 3

[0144] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Aspheric 23.29 3.18 Chalcogenide glass 2 Aspheric 25.38 2 - 3 Aperture unlimited -1.38 - 4 Aspheric 11.76 3.68 Chalcogenide glass 5 Aspheric 9.4 4.91 - 6 Structural surface unlimited 0.3 silicon 7 Spherical unlimited 7.9 - 8 Aspheric 51.8 4.66 Chalcogenide glass 9 Aspheric -107.12 0.1 - 10 Spherical unlimited 0.7 germanium 11 Spherical unlimited 9.1

[0145] The analysis of each surface in Table 3-2 can refer to Example 1, and no further analysis is performed in this example.

[0146] Surface 1, surface 2, surface 4, surface 5, surface 8 and surface 9 are all even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0147]

[0148] 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; c is the curvature of the aspherical surface, c=1 / R, R is the radius of curvature of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 1, surface 2, surface 4, surface 5, surface 8 and surface 9 can be obtained from Table 3-3.

[0149] Table 3-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 3

[0150]

[0151]

[0152] The even-order aspheric coefficients of surface 1, surface 2, surface 4, surface 5, surface 8 and surface 9 can be obtained from Table 3-3 and will not be elaborated here one by one.

[0153] Fig.12 This is a phase distribution diagram of the superlens 30 of the far-infrared optical system 100 provided in Example 3 at a main wavelength of 10 microns, wherein the horizontal axis is a coordinate axis established with the center of the superlens 30 as the origin.

[0154] See also Fig.13 , Fig.13 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at 20° C. is shown. Fig.13 The horizontal axis in is the Y-axis field of view, and its unit is degree; Fig.13 The vertical axis is the MTF value. Fig.13 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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 entire field of view, the MTF is greater than 0.28, and the imaging quality of the far-infrared optical system 100 is excellent.

[0155] See also Fig.14 , Fig.14 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at -40°C is shown. Fig.14 The horizontal axis in is the Y-axis field of view, and its unit is degree; Fig.14 The vertical axis is the MTF value. Fig.14The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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.14 It can be seen that within the entire field of view, the MTF is greater than 0.29, and the imaging quality of the far-infrared optical system 100 is excellent.

[0156] See also Fig.15 , Fig.15 The MTF field curve of the far-infrared optical system 100 provided in Example 3 at 80° C. is shown. Fig.15 The horizontal axis in is the Y-axis field of view, and its unit is degree; Fig.15 The vertical axis is the MTF value. Fig.15 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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.15 It can be seen that within the entire field of view, the MTF is greater than 0.24, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0157] comprehensive Figures 13 to 15 It can be seen that when the temperature changes within the range of -40°C-80°C, the MTF of the far-infrared optical system 100 provided in Example 3 is less affected by the temperature change, that is, the far-infrared optical system 100 provided in Example 3 has an excellent athermal effect within the range of -40°C-80°C.

[0158] Example 4

[0159] Fig.16 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 4. Fig.16 The mid-infrared optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, a first aspheric lens 10, an aperture 50, a second aspheric lens 20, a super lens 30, a third aspheric lens 40, and a protective glass 60, wherein the micro-nano structure 320 is disposed on the object side of the substrate 310. Some parameters of the far-infrared optical system 100 provided in Example 4 are shown in Table 4-1.

[0160] Table 4-1. Partial parameters of the far-infrared optical system 100 provided in Example 4

[0161] parameter data Total optical length (TTL) 35.17mm Maximum field of view (2ω) 46° F-number 1.0 Effective focal length 24mm Working band Far infrared light (10±2μm)

[0162] As can be seen from Table 4-1, the working band of the far-infrared optical system 100 is 8 μm-12 μm, and the total optical length of the far-infrared optical system 100 is relatively short, only 35.17 mm, so 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 1.0, which can ensure that the far-infrared optical system 100 has a large amount of light entering.

[0163] Along the optical axis S from the object plane A to the image plane B, starting from the first aspheric lens 10, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 4-2.

[0164] Table 4-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 4

[0165]

[0166]

[0167] The analysis of each surface in Table 4-2 can refer to Example 1, and no further analysis is performed in this example.

[0168] Surface 1, surface 2, surface 4, surface 5, surface 8 and surface 9 are all even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0169]

[0170] 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; c is the curvature of the aspherical surface, c = 1 / R, R is the radius of curvature of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of Surface 1, Surface 2, Surface 4, Surface 5, Surface 8 and Surface 9 can be obtained from Table 4-3.

[0171] Table 4-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 4

[0172] Surface serial number k A B C D E F G 1 -2.96E-01 7.77E-06 -1.57E-07 1.88E-09 -2.66E-11 1.57E-13 -5.16E-16 4.33E-19 2 -8.62E-02 -1.17E-04 1.25E-06 -1.57E-08 1.16E-10 -4.86E-13 8.29E-16 -3.34E-20 4 -4.61E-02 -1.14E-04 1.93E-07 -1.11E-08 1.25E-11 7.31E-13 -4.60E-15 2.06E-18 5 -1.34E-01 3.09E-06 -2.91E-06 1.95E-08 -5.82E-10 9.82E-12 -7.04E-14 7.50E-17 8 4.65E+00 1.35E-05 -8.85E-09 -9.38E-10 9.85E-12 -5.32E-14 1.14E-16 -3.13E-20 9 2.67E+01 2.33E-05 -3.47E-08 -5.44E-10 5.58E-12 -3.08E-14 5.28E-17 6.05E-20

[0173] The even-order aspheric coefficients of surface 1, surface 2, surface 4, surface 5, surface 8 and surface 9 can be obtained from Table 4-3 and will not be elaborated here one by one.

[0174] Fig.17 This is a phase distribution diagram of the superlens 30 of the far-infrared optical system 100 provided in Example 4 at a main wavelength of 10 microns, wherein the horizontal axis is a coordinate axis established with the center of the superlens 30 as the origin.

[0175] See also Fig.18 , Fig.18 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at 20° C. is shown. Fig.18 The horizontal axis in is the Y-axis field of view, and its unit is degree; Fig.18 The vertical axis is the MTF value. Fig.18 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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.18 It can be seen that within the entire field of view, the MTF is greater than 0.25, and the imaging quality of the far-infrared optical system 100 is excellent.

[0176] See also Fig.19 , Fig.19 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at -40°C is shown. Fig.19 The horizontal axis in is the Y-axis field of view, and its unit is degree; Fig.19 The vertical axis is the MTF value. Fig.19 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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 entire field of view, the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is excellent.

[0177] See also Fig. 20 , Fig. 20 The MTF field curve of the far-infrared optical system 100 provided in Example 4 at 80° C. is shown. Fig. 20 The horizontal axis in is the Y-axis field of view, and its unit is degree; Fig. 20 The vertical axis is the MTF value. Fig. 20 The MTF of 14lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 28lp / 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 entire field of view, the MTF is greater than 0.28, and the imaging quality of the far-infrared optical system 100 is excellent.

[0178] comprehensive Figures 18 to 20It can be seen that when the temperature changes within the range of -40°C-80°C, the MTF of the far-infrared optical system 100 provided in Example 4 is less affected by the temperature change. Therefore, the far-infrared optical system 100 provided in Example 4 has an excellent athermal effect within the range of -40°C-80°C.

[0179] 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.

[0180] Table 5. Parameters of the far-infrared optical system 100 provided in various embodiments

[0181]

[0182]

[0183] The present application also provides a far-infrared optical lens (not shown), which includes an imaging detector (not shown) and the above-mentioned far-infrared optical system 100. The specific structure of the far-infrared optical system 100 can be referred to above and will not be repeated here. The imaging detector is arranged on the image plane B of the far-infrared optical system 100, and the imaging detector includes but is not limited to CMOS (Complementary Metal Oxide Semiconductor, referred to as CMOS, complementary metal oxide semiconductor) and CCD (Charge Coupled Device, referred to as CCD, charge coupled device).

[0184] 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 includes, from the object side to the image side along the optical axis, a first aspheric lens, a second aspheric lens, a super lens and a third aspheric lens; the optical power of the first aspheric lens is positive, the object side surface of the first aspheric lens is convex to the object side, and the image side surface of the first aspheric lens is convex to the object side; the object side surface of the second aspheric lens is convex to the object side, and the image side surface of the second aspheric lens is convex to the object side; the optical power of the super lens is positive; the optical power of the third aspheric lens is positive, and the object side surface of the third aspheric lens is convex to the object side.

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 f m is the focal length of the superlens, and the f gm1 is the focal length of the first aspheric lens, and the f gm2 is the focal length of the second aspheric lens, the f gm3 is the focal length of the third aspheric lens, and L1 is the distance between the object side surface of the first aspheric lens and the object side surface of the second aspheric lens on the optical axis.

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 θ max is the absolute value of the maximum phase difference of the metalens, and the f m is the focal length of the metalens, and D m is the effective diameter of the superlens.

4. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, L2 is the distance between the object side surface of the super lens and the object side surface of the first aspheric lens on the optical axis, and D m is the effective diameter of the superlens.

5. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, f is the effective focal length of the far-infrared optical system, and f gm1 is the focal length of the first aspheric lens, and the f m is the focal length of the superlens, and the f gm3 is the focal length of the third aspheric lens.

6. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the R 1gm1 is the radius of curvature of the object side of the first aspheric lens, and the R 2gm1 is the radius of curvature of the image side surface of the first aspheric lens, and the R 1gm2 is the radius of curvature of the object side of the second aspheric lens, and the R 2gm2 is the radius of curvature of the image-side surface of the second aspheric 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 FOV is the maximum field of view angle of the far-infrared optical system, f is the effective focal length of the far-infrared optical system, and the BFL is the optical back focus of the far-infrared optical system.

8. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the D m is the effective diameter of the metalens, the FNO is the aperture number of the far-infrared optical system, and f is the effective focal length of the far-infrared optical system.

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 disposed on the object side of the first aspherical lens; or, the aperture is disposed 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