Far infrared optical system and far infrared optical lens

Abstract

The utility model discloses a far-infrared optical system and a far-infrared optical lens. The far-infrared optical system sequentially comprises a super lens and a refraction lens from an object side to an image side along an optical axis. The refraction lens is a positive lens, the surface, close to the object side, of the refraction lens protrudes towards the image side, and the surface, close to the image side, of the refraction lens protrudes towards the image side; the super lens is a positive lens and comprises a substrate and a micro-nano structure, and the micro-nano structure is arranged on at least one side face of the substrate in the direction from the object side to the image side along the optical axis. Wherein the far infrared optical system meets the following condition: # imgabs0 #, V2 is the abbe number of the refraction lens, and Vm is the abbe number of the super lens. The total optical length of the far-infrared optical system is short, so that the far-infrared optical system has a relatively small size, the imaging quality of the far-infrared optical system is good, and the far-infrared optical system has the advantages of being small in size and good in imaging quality at the same time.

Description

Technical Field

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

[0002] In an optical system, the imaging quality and volume of the optical system are usually mutually constrained. Specifically, in order to obtain a higher imaging quality, multiple lenses are usually required, but a larger number of lenses will result in a larger volume of the optical system. The imaging quality of an optical system with fewer lenses is usually average. That is, the optical system in the prior art usually cannot take into account both the advantages of smaller volume and higher imaging quality. Utility Model Content

[0003] In response to the above technical problems, the embodiments of the present application provide a far-infrared optical system and a far-infrared optical lens, which aim to solve the problem that the far-infrared optical system in the prior art cannot take into account the advantages of smaller size and higher imaging quality.

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

[0005] Wherein, the far-infrared optical system satisfies: Wherein, V2 is the Abbe number of the refractive lens, and V m is the Abbe number of the superlens.

[0006] In some embodiments, the refractive lens is an aspherical lens.

[0007] In some embodiments, the far-infrared optical system satisfies: Wherein, Φ2 is the focal length of the refractive lens, and Φ m is the optical power of the metalens.

[0008] In some embodiments, one or more of the two side surfaces of the substrate along the optical axis from the object side to the image side is provided with the micro-nano structure, and the far-infrared optical system satisfies:

[0009] In some embodiments, the micro-nano structure is disposed on both sides of the substrate along the optical axis from the object side to the image side, and the far-infrared optical system satisfies:

[0010]

[0011] In some embodiments, the far-infrared optical system satisfies: Wherein, c1 is the curvature of the surface of the refractive lens close to the object side, c2 is the curvature of the surface of the refractive lens close to the image side, and T is the thickness of the refractive lens on the optical axis.

[0012] In some embodiments, the far-infrared optical system satisfies: Wherein, the r2 is half of the effective aperture of the refractive lens, and the BFL is the optical back focal length of the optical system.

[0013] In some embodiments, the micro-nano structure is provided on both sides of the substrate along the optical axis from the object side to the image side, the surface of the metalens close to the object side is the front surface of the metalens, the surface of the metalens close to the image side is the rear surface of the metalens, the front surface of the metalens or the rear surface of the metalens has a phase gradient inflection point, and the metalens satisfies: Wherein, L is the distance from the phase gradient inflection point to the center of the superlens, and r m It is half of the effective aperture of the superlens.

[0014] In some embodiments, the micro-nano structure is disposed on two side surfaces of the substrate along the optical axis from the object side to the image side, and the refractive lens is a spherical lens or an aspherical lens.

[0015] In some embodiments, the far-infrared optical system further comprises an aperture, and the aperture is disposed on a side of the superlens close to the object side;

[0016] or,

[0017] The aperture is arranged on the surface of the super lens close to the object side;

[0018] or,

[0019] The aperture is disposed between the super lens and the refractive lens;

[0020] or,

[0021] The aperture is arranged on the surface of the refractive lens close to the image side;

[0022] or,

[0023] The aperture is arranged on a side of the refractive lens close to the image side.

[0024] In some embodiments, the aperture is disposed on a surface of the superlens close to the object side; or, the aperture is disposed on a surface of the refractive lens close to the image side.

[0025] 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.

[0026] In some embodiments, the far-infrared optical lens also includes a lens barrel and a spacer, the lens barrel is provided with a mounting through hole, the mounting through hole includes a first hole segment and a second hole segment along the optical axis from the object side to the image side, the diameter of the first hole segment is larger than the diameter of the second hole segment; the refractive lens is accommodated in the second hole segment, the super lens is accommodated in the first hole segment, and the super lens is abutted against the refractive lens; the spacer is accommodated in the first hole segment, the spacer is located on the side of the super lens away from the refractive lens, and the spacer is abutted against the super lens.

[0027] In some embodiments, the far-infrared optical lens further includes a pressure ring, which is received in the first hole section, is located on a side of the spacer away from the superlens, is connected to the lens barrel, and abuts against the spacer.

[0028] The far-infrared optical system provided by the present application includes: a super lens and a refractive lens in order from the object side to the image side along the optical axis. The refractive lens is a positive lens, and the surface of the refractive lens close to the object side is convex to the image side, and the surface of the refractive lens close to the image side is convex to the image side; the super lens is a positive lens, and the super lens includes a substrate and a micro-nano structure, and at least one side of the substrate along the direction from the object side to the image side of the optical axis is provided with a micro-nano structure. The far-infrared optical system meets the following requirements: Where V2 is the Abbe number of the refractive lens, V m The far-infrared optical system in the present application has a relatively short total optical length, so that the far-infrared optical system has a relatively small volume, and the imaging quality of the far-infrared optical system is better, so that the far-infrared optical system can take into account the advantages of both small volume and good imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] Figure 1 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0031] Figure 2 The phase distribution diagram of the front surface or the back surface of the metalens of the far-infrared optical system in one embodiment of the present application is shown.

[0032] Figure 3 The MTF field of view curve of the far-infrared optical system in one embodiment of the present application is shown.

[0033] Figure 4 A point diagram of a far-infrared optical system in one embodiment of the present application is shown.

[0034] Figure 5 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0035] Figure 6 The MTF field of view curve of the far-infrared optical system in one embodiment of the present application is shown.

[0036] Figure 7 A point diagram of a far-infrared optical system in one embodiment of the present application is shown.

[0037] Figure 8 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0038] Fig. 9 The MTF field of view curve of the far-infrared optical system in one embodiment of the present application is shown.

[0039] Fig.10 A point diagram of a far-infrared optical system in one embodiment of the present application is shown.

[0040] Fig.11 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0041] Fig.12 The MTF field of view curve of the far-infrared optical system in one embodiment of the present application is shown.

[0042] Fig.13 A point diagram of a far-infrared optical system in one embodiment of the present application is shown.

[0043] Fig.14 The phase distribution diagram of the front surface of the metalens of the far-infrared optical system in one embodiment of the present application is shown.

[0044] Fig.15 The phase distribution diagram of the rear surface of the metalens of the far-infrared optical system in one embodiment of the present application is shown.

[0045] Fig.16 A schematic diagram of the structure of a far-infrared optical lens in an embodiment of the present application is shown.

[0046] Reference numerals

[0047] 100. Far infrared optical system;

[0048] 1. Superlens; 11. Substrate; 12. Micro-nanostructure;

[0049] 2. Refractive lens;

[0050] 3. Aperture;

[0051] 4. Protective parts;

[0052] A, object plane; B, image plane; S, optical axis;

[0053] 200, lens barrel; 2001, mounting through hole; 2001a, first hole section; 2001b, second hole section;

[0054] 300, spacer;

[0055] 400, press circle;

[0056] 1000. Far infrared optical lens. DETAILED DESCRIPTION

[0057] 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.

[0058] 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.

[0059] See also Figure 1 , Figure 1 FIG. 1 shows a schematic diagram of the structure layout of an optical system in an embodiment of the present application, wherein the optical axis S is the center line of the light beam. Figure 1In the figure, the object to be measured is located on the left side of the leftmost lens, that is, the object side is located on the left side of the leftmost lens, and the object plane A is located on the object side. The image formed by the optical system 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.

[0060] The far-infrared optical system 100 includes a super lens 1 and a refractive lens 2 , which are sequentially arranged along an optical axis S from the object side to the image side.

[0061] The refractive lens 2 is a positive lens. The surface of the refractive lens 2 close to the object side is convex toward the image side, and the surface of the refractive lens 2 close to the image side is convex toward the image side.

[0062] The superlens 1 is a positive lens. The superlens 1 includes a substrate 11 and a superstructure unit located on the surface of the substrate 11. A micro-nano structure 12 is provided at the vertex and / or center of the superstructure unit. The filling material between the micro-nano structures 12 is air or other materials transparent in the far-infrared band. The micro-nano structure 12 is located on at least one side of the substrate 11 along the optical axis S from the object side to the image side. The number of layers of the micro-nano structure 12 can be one layer, two layers, or more than two layers. According to the phase modulation method adopted, the corresponding phase modulation formula can be adaptively used to configure the various parameters of the micro-nano structure 12, so that the superlens 1 can achieve corresponding optical performance.

[0063] The far-infrared optical system 100 satisfies conditional formula 1: Among them, V m is the Abbe number of the super lens 1, and V2 is the Abbe number of the refractive lens 2. Conditional equation 1 shows the ratio of the Abbe number of the super lens 1 to the Abbe number of the refractive lens 2. According to the primary achromatic formula It can be seen that the sum of the ratios of the optical power and the Abbe number of the optical system approaches 0, and the primary chromatic aberration of the optical system can be better controlled. Abbe number V of superlens 1 m Depends on wavelength, Wherein, λ2 is the central wavelength of the working band of the far-infrared optical system 100, λ3 is the minimum wavelength in the working band of the far-infrared optical system 100, and λ1 is the maximum wavelength in the working band of the far-infrared optical system 100. Taking the working band of the far-infrared optical system 100 as a micrometer to b micrometers, and a<b as an example, then, λ1=b micrometers, λ3 = a micrometer. Therefore, based on the optical power relationship between the superlens 1 and the refractive lens 2, the Abbe number V of the superlens 1 is m When the Abbe number V2 of the refractive lens 2 satisfies the conditional expression 1, the chromatic aberration of the far-infrared optical system 100 can be effectively corrected.

[0064] It is worth mentioning that the far-infrared optical system 100 does not have to satisfy the above-mentioned primary achromatic aberration formula to effectively correct chromatic aberration. When designing the far-infrared optical system 100, the margin of primary chromatic aberration is often used to correct higher-order chromatic aberration. Therefore, when the upper limit of conditional formula 1 is relatively generous, the Abbe number of the material may not satisfy the primary achromatic aberration, but the Abbe number is used in conjunction with the primary chromatic aberration to correct higher-order chromatic aberration.

[0065] In the present application, the total optical length of the far-infrared optical system 100 is relatively short, so that the far-infrared optical system 100 has a relatively small volume, and the imaging quality of the far-infrared optical system 100 is better, so that the far-infrared optical system 100 can simultaneously take into account the advantages of smaller volume and better imaging quality.

[0066] In some embodiments, the micro-nano structure 12 is a negative micro-nano structure, and the far-infrared optical system 100 further includes a first anti-reflection film (not shown), which is disposed on a side of the negative micro-nano structure away from the substrate to increase the transmittance of the negative micro-nano structure to light.

[0067] Furthermore, in some embodiments, the micro-nano structure 12 is a negative micro-nano structure, the first anti-reflection film is arranged on the side of the negative micro-nano structure away from the substrate, and the far-infrared optical system 100 also includes a second anti-reflection film (not shown), the second anti-reflection film is arranged on the side of the substrate 11 away from the negative micro-nano structure, and the second anti-reflection film is used to increase the transmittance of the metalens 1 to light in a specific band of far infrared.

[0068] In some embodiments, the micro-nanostructure 12 is a positive micro-nanostructure.

[0069] In some embodiments, the micro-nano structure 12 has one layer, two layers, or more than three layers.

[0070] Furthermore, in some embodiments, the micro-nano structure 12 is provided with a layer, which can make the superlens 11 have a larger and expected optical focal length, and also make the superlens 11 have better processability.

[0071] Furthermore, in some embodiments, the micro-nano structure 12 has two or three layers, which can make the superlens 11 have a larger and expected optical focal length.

[0072] In some embodiments, the micro-nano structure 12 is located on a surface of the substrate 11 close to the object side.

[0073] In some embodiments, the micro-nano structure 12 is located on a surface of the substrate 11 close to the image side.

[0074] It should be noted that, under the premise that the superlens 1 has the expected performance, the positive and negative of the micro-nano structure 12, the number of layers of the micro-nano structure 12, and the location of the micro-nano structure 12 can be freely combined.

[0075] It should be understood that when the surface of the substrate 11 close to the object side and the surface close to the image side are both provided with the micro-nano structure 12, the number of layers of the micro-nano structure 12 on the surface of the substrate 11 close to the object side and the number of layers of the micro-nano structure 12 on the surface of the substrate 11 close to the image side may be equal or unequal, as long as the metalens 1 has the expected optical performance.

[0076] In some embodiments, the refractive lens 2 is an aspherical lens.

[0077] In some embodiments, the refractive lens 2 is an aspherical lens, and the far-infrared optical system 100 satisfies conditional formula 2: Wherein, Φ2 is the focal length of the refractive lens 2; Φ m is the focal power of superlens 1, Φ m The dimension of is the same as that of Φ2, both of which are diopters (Diopter, abbreviated as D). Conditional formula 2 shows the relationship between the optical power of metalens 1 and refractive lens 2. The lower limit of the conditional formula shows that metalens 1 can provide an optical power almost equal to that of refractive lens 2, and the lower limit of conditional formula 2 can avoid the introduction of large chromatic aberration by metalens 1 due to the fact that the optical power of metalens 1 is significantly greater than that of refractive lens 2. The upper limit of conditional formula 2 can ensure that metalens 1 can provide sufficient optical power in the optical system, thereby controlling the optical power that refractive lens 2 needs to provide within a reasonable range, reducing the optical power pressure of refractive lens 2, and avoiding the difficulty in manufacturing refractive lens 2 due to the large curvature caused by excessive optical power, so that refractive lens 2 has good processability.

[0078] In some embodiments, the refractive lens 2 is an aspherical lens, and the micro-nano structure 12 is disposed on the surface of the substrate 11 facing the object side; or, the micro-nano structure 12 is disposed on the surface of the substrate 11 facing the image side. That is, when only one of the two side surfaces of the substrate 11 along the optical axis S from the object side to the image side is provided with the micro-nano structure 12, the far-infrared optical system 100 satisfies conditional formula 3:

[0079] Conditional equation 3 characterizes the optical power distribution relationship between the superlens 1 and the refractive lens 2. When one and only one of the two side surfaces of the substrate 11 along the optical axis S from the object side to the image side is provided with the micro-nano structure 12, the optical power provided by the superlens 1 is approximately five times the optical power of the refractive lens 2. In this case, the negative dispersion introduced by the superlens 1 and the dispersion of the refractive lens 2 can compensate each other, thereby correcting the chromatic aberration of the far-infrared optical system 100.

[0080] Further, in some embodiments, when the refractive lens 2 is an aspherical lens and one or more of the two side surfaces of the substrate 11 along the optical axis S from the object side to the image side is provided with the micro-nano structure 12, the far-infrared optical system 100 satisfies conditional formula 4: In this case, the negative dispersion introduced by the superlens 1 and the dispersion of the refractive lens 2 can compensate each other, so that the chromatic aberration of the far-infrared optical system 100 can be better corrected, and the far-infrared optical system 100 can have smaller chromatic aberration.

[0081] In the present application, when the two side surfaces of the substrate 11 along the optical axis S from the object side to the image side are provided with a micro-nano structure 12, the surface of the superlens 1 close to the object side is the front surface of the superlens 1, and the front surface of the superlens 1 refers to the substrate 11 and the micro-nano structure 12 located on the substrate 11 close to the object side; the surface of the superlens 1 close to the image side is the rear surface of the superlens 1, and the rear surface of the superlens 1 refers to the substrate 11 and the micro-nano structure 12 located on the substrate 11 close to the image side.

[0082] In some embodiments, the micro-nano structures 12 are disposed on both sides of the substrate 11 along the optical axis S from the object side to the image side, and the far-infrared optical system 100 satisfies conditional formula 5: Since the surface of the superlens 1 close to the object side and the surface of the superlens 1 close to the image side are both provided with the micro-nano structure 12, the phase gradient of the front surface of the superlens 1 can be complementary to the phase gradient of the rear surface of the superlens 1, which can correct the partial dispersion of the superlens 1 itself and reduce the chromatic aberration of the far-infrared optical system 100.

[0083] Furthermore, in some embodiments, the micro-nano structures 12 are provided on both sides of the substrate 11 along the optical axis S from the object side to the image side, and the far-infrared optical system 100 satisfies conditional formula 6: The chromatic aberration of the far-infrared optical system 100 can be further reduced.

[0084] In some embodiments, when the refractive lens 2 is an aspherical lens and the two side surfaces of the substrate 11 along the optical axis S from the object side to the image side are provided with a micro-nano structure 12, the optical power of the front surface of the superlens 1 and the rear surface of the superlens 1 are any of the following:

[0085] (1) The optical focal length of the front surface of the superlens 1 is positive, and the optical focal length of the rear surface of the superlens 1 is negative. At this time, the front surface of the superlens 1 and the rear surface of the superlens 1 are complementary, and part of the chromatic aberration of the superlens 1 itself can be corrected.

[0086] (2) The optical focal length of the front surface of the superlens 1 is negative, and the optical focal length of the rear surface of the superlens 1 is positive. At this time, the front surface of the superlens 1 and the rear surface of the superlens 1 are complementary, and part of the chromatic aberration of the superlens 1 itself can be corrected.

[0087] (3) The optical power of the front surface of the super lens 1 is a positive value, and the optical power of the rear surface of the super lens 1 is also a positive value.

[0088] In some embodiments, the refractive lens 2 is an aspherical lens, and the far-infrared optical system 100 satisfies conditional equation 7: Wherein, c1 is the curvature of the surface of the refractive lens 2 close to the object side, and the unit of c1 is mm -1 c2 is the curvature of the surface of the refractive lens 2 close to the image side, and the unit of c2 is mm -1 T is the thickness of the refractive lens 2 on the optical axis S, and the unit of T is mm.

[0089] Conditional formula 7 shows the relationship between the curvature and thickness of the refractive lens 2. The upper limit of conditional formula 7 can prevent the refractive lens 2 from being difficult to process due to excessive curvature, and can also prevent the refractive lens 2 from being too thin and causing difficulty in processing. The lower limit of conditional formula 7 has the following functions: (1) It can ensure that the refractive lens 2 provides sufficient focal length and can ensure that the refractive lens 2 has a suitable thickness, so that the refractive lens 2 has good processability. (2) It prevents the refractive lens 2 from being too thick, resulting in an excessively large volume of the far-infrared optical system 100.

[0090] Further, in some embodiments, the refractive lens 2 is an aspherical lens, and the far-infrared optical system 100 satisfies conditional formula eight: Conditional expression 8 can achieve a balance between the optical power, thickness and processing difficulty of the refractive lens 2.

[0091] In some embodiments, the refractive lens 2 is an aspherical lens, and the far-infrared optical system 100 satisfies conditional formula 9: Wherein, r2 is half of the effective aperture of the refractive lens 2, and the dimension of r2 is a length unit. BFL is the optical back focal length of the optical system, and in the present application, BFL is the distance between the surface of the refractive lens 2 close to the object side and the image plane B on the optical axis S, and the dimension of BFL is a length unit. The dimension of BFL is the same as that of r, both of which are length units, for example, millimeters.

[0092] Conditional formula nine indicates the ratio of half of the effective aperture of the refractive lens 2 to the optical back focal length of the far-infrared optical system 100. The ratio of conditional formula nine can reflect the working F number of the far-infrared optical system 100. The larger the value of conditional formula nine, the larger the working F number of the far-infrared optical system 100. The larger the working F number of the far-infrared optical system 100, the larger the amount of light entering the far-infrared optical system 100, and the better the response rate of the far-infrared optical system 100. The upper limit of conditional formula nine can avoid the increase of the material cost of the refractive lens 2 due to the excessively large effective aperture. At the same time, the upper limit of conditional formula nine can also prevent the far-infrared optical system 100 from being difficult to assemble due to the too short optical back focal length. The lower limit of conditional formula nine can avoid the working F number of the far-infrared optical system 100 being too small, and can ensure that the far-infrared optical system 100 has a working F number that meets the preset requirements.

[0093] In some embodiments, the refractive lens 2 is an aspherical lens, and the two sides of the substrate 11 along the optical axis S from the object side to the image side are provided with micro-nano structures 12, and the phase gradient of the front surface of the superlens 1 is complementary to the phase gradient of the rear surface of the superlens 1. Figure 2 , Figure 2 The horizontal axis is the distance between each position on the superlens 1 and the center of the superlens 1. Figure 2 The vertical axis represents the phase of each position on the lens 1. The front surface of the metalens 1 or the rear surface of the metalens 1 has a phase gradient inflection point P. The phase gradient inflection point P refers to the point where the monotonicity of the phase gradient changes. The metalens 1 satisfies the conditional formula 10: Wherein, L is the distance from the phase gradient inflection point P to the center of the superlens 1, and the dimension of L is the unit of length. m is half of the effective aperture of the superlens 1. The effective aperture of the superlens 1 refers to the maximum light-passing diameter of the superlens 1. m The dimension of is the unit of length. m It has the same dimension as L, which is a unit of length, for example, millimeters.

[0094] Conditional formula ten represents the percentage of the area on the surface of the metalens 1 having the phase gradient inflection point P used to provide a complementary phase. When the optical focal length provided by the metalens 1 is large enough, it will inevitably lead to larger chromatic aberration, especially in the paraxial region. Therefore, in order to correct the chromatic aberration, at least 60% of the area on the surface of the metalens 1 having the phase gradient inflection point P is the compensation area, and the compensation area is used to provide an opposite phase gradient for the other surface of the metalens 1 (the surface not containing the phase gradient inflection point P) to correct the chromatic aberration in the edge area of ​​the metalens 1. When the compensation area on the surface of the metalens 1 having the phase gradient inflection point P accounts for 100%, it indicates that the surface of the metalens 1 having the phase gradient inflection point P provides a negative focal length, and the entire surface of the metalens 1 having the phase gradient inflection point P is used to provide a compensating phase. When the compensation area is between 40% and 100%, the paraxial area of ​​the surface of the metalens 1 having the phase gradient inflection point P provides positive optical power to increase the overall light convergence ability of the metalens 1; the paraxial area of ​​the surface of the metalens 1 having the phase gradient inflection point P provides a compensation phase to correct chromatic aberration.

[0095] It is worth mentioning that the surface of the superlens 1 having the phase gradient inflection point P can be the front surface of the superlens 1 or the back surface of the superlens 1 .

[0096] In some embodiments, at least one of the two side surfaces of the substrate 11 along the optical axis S from the object side to the image side is provided with a structure, and the refractive lens 2 is an aspherical lens. Specifically, when the superlens 1 satisfies case A and case B, the refractive lens 2 is an aspherical lens.

[0097] Case A: Only the surface of the substrate 11 facing the object side is provided with structures, and the refractive lens 2 is an aspherical lens.

[0098] Case B: Only the surface of the substrate 11 facing the image side is provided with structures, and the refractive lens 2 is an aspherical lens.

[0099] For the above-mentioned cases A and B, since only one of the front surface or the rear surface of the metalens 1 is provided with the micro-nano structure 12, at this time, the optical focal length that the metalens 1 can provide is limited, and the aberrations introduced by the large edge field of view, especially the field curvature and coma, cannot be effectively corrected. Therefore, when the refractive lens 2 is an aspherical lens, the aberrations of the far-infrared optical system 100 can be effectively corrected, and the optical system can have better imaging quality.

[0100] In some embodiments, the two side surfaces of the substrate 11 along the optical axis S from the object side to the image side are provided with a micro-nano structure 12. In this case, since the front surface of the superlens 1 and the rear surface of the superlens 1 cooperate with each other to correct the field curvature and coma of the far-infrared optical system 100, the refractive lens 2 only needs to provide an optical focal length that meets the expected requirements, that is, the refractive lens 2 can be an aspherical lens or a spherical lens.

[0101] Furthermore, in some embodiments, when the front and rear surfaces of the metalens 1 are both provided with a micro-nano structure 12 and the refractive lens 2 is an aspherical lens, the aberration of the far-infrared optical system 100 can be more effectively controlled, thereby enabling the far-infrared optical system 100 to have better imaging quality.

[0102] Further, in some embodiments, the micro-nano structures 12 are provided on both sides of the substrate 11 along the optical axis S from the object side to the image side, and the refractive lens 2 is a spherical lens. Generally, the manufacturing cost of a spherical lens is lower than that of an aspherical lens, so when the refractive lens 2 is a spherical lens, the production cost of the far-infrared optical system 100 can be reduced.

[0103] In some embodiments, the far-infrared optical system 100 further includes an aperture 3, which is used to limit the amount of light entering the far-infrared optical system 100 to ensure that the far-infrared optical system 100 can work effectively and generate high-quality images. The position of the aperture 3 can be any of the following:

[0104] (1) The aperture 3 is provided on the object side of the super lens 1 .

[0105] (2) The aperture 3 is provided on the front surface of the super lens 1 .

[0106] (3) The aperture 3 is provided between the super lens 1 and the refractive lens 2 .

[0107] (4) The aperture 3 is provided on the rear surface of the refractive lens 2 .

[0108] (5) The aperture 3 is provided on the image side of the refractive lens 2 .

[0109] Furthermore, in some embodiments, the aperture 3 is disposed on the surface of the superlens 1 close to the object side to reduce the volume of the far-infrared optical system 100 .

[0110] Furthermore, in some embodiments, the aperture 3 is disposed on the surface of the refractive lens 2 close to the image side to reduce the volume of the far-infrared optical system 100 .

[0111] In some embodiments, the aperture 3 is a layered structure, for example, a coating, so that the aperture 3 can be disposed on the front surface or the back surface of the super lens 1 .

[0112] In some embodiments, the far-infrared optical system 100 further includes a protective member 4, which is used to protect each lens. The protective member 4 can transmit light, and the protective member 4 is located on the side of the refractive lens 2 close to the image side along the optical axis S. The protective member 4 includes but is not limited to a protective glass. It should be noted that if the aperture 3 is located on the side of the refractive lens 2 close to the image side, the protective member 4 is located on the side of the aperture 3 close to the image side.

[0113] The working wavelength of the far-infrared optical system 100 is 8 microns to 12 microns. The target requirements of the far-infrared optical system 100 for various system parameters are shown in Table 1.

[0114] Table 1. Target requirements for various system parameters of far-infrared optical system 100

[0115]

[0116] As shown in Table 1, the total optical length of the far-infrared optical system 100 must be less than 14 mm, the maximum field angle of the far-infrared optical system 100 must be between 59.752 degrees and 63.448 degrees, the distortion of the far-infrared optical system 100 must be less than 15%, and the F number of the far-infrared optical system 100 must be less than or equal to 1.0.

[0117] 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.

[0118] Example 1

[0119] Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 1. Figure 1The mid-to-far infrared optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, a metalens 1, an aperture 3, a refractive lens 2, and a protective member 4, wherein the aperture 3 is located on the surface of the metalens 1 close to the image side, and the metalens 1 has and only has a rear surface provided with a micro-nano structure 12. The parameters of the far-infrared optical system 100 provided in Example 1 are shown in Table 2.

[0120] Table 2. Partial parameters of various systems of the far-infrared optical system 100 provided in Example 1

[0121]

[0122]

[0123] As can be seen from Table 2, the total optical length of the far-infrared optical system 100 is 9.82 mm, which is less than 14 mm. Therefore, the total optical length of the far-infrared optical system 100 meets the target requirements. The maximum field angle of the far-infrared optical system 100 is 61.6 degrees, which is between 59.752 degrees and 63.448 degrees. Therefore, the maximum field angle of the far-infrared optical system 100 meets the target requirements. The F number of the far-infrared optical system 100 is 1.0. Therefore, the F number of the far-infrared optical system 100 meets the target requirements.

[0124] Along the direction of the optical axis S from the image plane B to the object plane A, each surface in the far-infrared optical system 100 is numbered starting from the object plane A, and the parameters of each surface are summarized to obtain the following Table 3.

[0125] Table 3. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 1

[0126] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Physical surface unlimited unlimited - 2 Spherical unlimited 0.30 silicon 3 Metasurface (aperture) unlimited 0.40 - 4 Aspheric -9.53 4.45 Sulfur 5 Aspheric -5.15 4.28 - 6 Spherical surface (protective part) unlimited 0.21 silicon 7 Spherical unlimited 0.10 - 8 Image plane - - -

[0127] For each surface in Table 3, surface 1 is the object surface A. Surface 2 is the surface of the metalens 1 close to the object side, surface 3 is the surface of the metalens 1 close to the image side, the micro-nano structure 12 is located on surface 3, and the aperture 3 is also located on surface 3. Surface 4 is the surface of the refractive lens 2 close to the object side, and surface 5 is the surface of the refractive lens 2 close to the image side. Surface 6 is the surface of the protective member 4 close to the object side, and surface 7 is the surface of the protective member 4 close to the image side. Surface 8 is the image surface B.

[0128] As can be seen from Table 3, the radius of curvature of surface 1 is infinite, that is, surface 1 is a plane, the distance between surface 1 and surface 2 is uncertain, and the material between surface 1 and surface 2 is air. Surface 2 is a spherical surface, the distance between surface 2 and surface 3 is 0.30 mm, and the material between surface 2 and surface 3 is silicon. Surface 3 is a spherical surface, the distance between surface 3 and surface 4 is 0.40 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 -9.53 mm, the distance between surface 4 and surface 5 is 4.45 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 4 is -5.15 mm, the distance between surface 5 and surface 6 is 4.28 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 0.21 mm, and the material between surface 6 and surface 7 is silicon. The curvature radius of surface 7 is infinite, that is, surface 7 is a plane, the distance between surface 7 and surface 8 is 0.10 mm, and the material between surface 7 and surface 8 is air.

[0129] Surface 4 and surface 5 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0130]

[0131] 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 SS; 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, E, F, G, etc. of surface 4 and surface 5 can be obtained from Table 4.

[0132] Table 4. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 1

[0133]

[0134] Please refer to Table 4. Taking surface 4 as an example, K is 23.74588410, A is -1.36156512E-02, B is 1.24545667E-02, C is -7.81630719E-03, D is 2.98839802E-03, E is -7.11591407E-04, F is 9.58561349E-05, and G is -5.42919325E-06. The specific parameters of surface 5 can be queried with reference to surface 4, which will not be repeated here.

[0135] See also Figure 3 , Figure 3The MTF (Modulation Transfer Function, MTF for short) curve of the far-infrared optical system 100 provided in Example 1 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 in is the MTF value. Figure 3 The MTF of 10.5lp / mm spatial frequency is listed as the sagittal image curve S2 and the meridional image curve T2 with the change of field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal image curve S3 and the meridional image curve T3 with the change of field of view, the MTF of 31.5lp / mm spatial frequency is listed as the sagittal image curve S4 and the meridional image curve T4 with the change of field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal image curve S5 and the meridional image curve T5 with the change of field of view. Figure 3 It can be seen that the MTF value of the far-infrared optical system 100 in the whole field of view is greater than 0.2, and the MTF value in the 0.8 field of view (24.64°) is greater than 0.3, so the imaging quality of the far-infrared optical system 100 is relatively good. In addition, the sagittal curve and the meridional curve at each spatial frequency are not much different, indicating that the far-infrared optical system 100 has good astigmatism control.

[0136] See also Figure 4 , Figure 4 The point diagram of the far-infrared optical system 100 provided in Example 1 is shown. Figure 4 It can be seen that the Airy disk radius of the far-infrared optical system 100 provided in Example 1 is 12.53 microns, and the RMS radius (root mean square error radius) of the light spot within the 0.9 field of view (27°) is smaller than the Airy disk radius. In addition, the RMS radius is about 12 microns, indicating that the spherical aberration of the far-infrared optical system 100 is well controlled.

[0137] Example 2

[0138] Figure 5 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 2. Figure 5 The mid-to-far infrared optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, a metalens 1, an aperture 3, a refractive lens 2, and a protective member 4, wherein the aperture 3 is located on the surface of the metalens 1 close to the image side, and the metalens 1 has and only has a rear surface provided with a micro-nano structure 12. The parameters of the far-infrared optical system 100 provided in Example 2 are shown in Table 5.

[0139] Table 5. Partial parameters of various systems of the far-infrared optical system 100 provided in Example 2

[0140] parameter data Total optical length (TTL) 10.7mm Maximum field of view (2ω) 61.6° F-number 1.0 Effective focal length 3.6mm Working band 8-12um

[0141] As can be seen from Table 5, the total optical length of the far-infrared optical system 100 is 10.7 mm, which is less than 14 mm. Therefore, the total optical length of the far-infrared optical system 100 meets the target requirements. The maximum field angle of the far-infrared optical system 100 is 61.6 degrees, which is between 59.752 degrees and 63.448 degrees. Therefore, the maximum field angle of the far-infrared optical system 100 meets the target requirements. The F number of the far-infrared optical system 100 is 1.0. Therefore, the F number of the far-infrared optical system 100 meets the target requirements.

[0142] Along the direction from the image plane B to the object plane A along the optical axis S, each surface in the far-infrared optical system 100 is numbered starting from the object plane A, and the parameters of each surface are summarized to obtain the following Table 6.

[0143] Table 6. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 2

[0144]

[0145]

[0146] The analysis of each surface in Table 6 can refer to Example 1 and will not be repeated here.

[0147] Surface 4 and surface 5 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 aspherical surface when the aspherical surface is at a height of r along the optical axis SS; 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, E, F, G, etc. of surface 4 and surface 5 can be obtained from Table 7.

[0150] Table 7. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 2

[0151]

[0152] The method for querying the specific parameters of surface 4 and surface 5 through Table 7 can be referred to Example 1, and will not be repeated here.

[0153] See also Figure 6 , Figure 6 FIG. 2 shows the MTF curve of the far-infrared optical system 100 provided in Example 2. Figure 6 The horizontal axis in is the Y-axis field of view, and its unit is degree. Figure 6 The vertical axis in is the MTF value. Figure 6The MTF of 10.5lp / mm spatial frequency is listed as the sagittal image curve S2 and the meridional image curve T2 with the change of field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal image curve S3 and the meridional image curve T3 with the change of field of view, the MTF of 31.5lp / mm spatial frequency is listed as the sagittal image curve S4 and the meridional image curve T4 with the change of field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal image curve S5 and the meridional image curve T5 with the change of field of view. Figure 6 It can be seen that the MTF value of the far-infrared optical system 100 in the entire field of view is greater than 0.3, so the far-infrared optical system 100 has good overall image resolution. In addition, the sagittal curve and the meridional curve at each spatial frequency are not much different, indicating that the far-infrared optical system 100 has good astigmatism control. The MTF value of the far-infrared optical system 100 at 0 field of view (0°, i.e., the center of the picture) and the MTF value at 1 field of view (30.8°) are not much different, indicating that the far-infrared optical system 100 has good field curvature control, indicating that the far-infrared optical system 100 has good overall imaging quality.

[0154] See also Figure 7 , Figure 7 The point diagram of the far-infrared optical system 100 provided in Example 2 is shown. Figure 7 It can be seen that the Airy disk radius of the far-infrared optical system 100 provided in Example 2 is 12.47 microns, and the root mean square error radius (RMS radius) of the light spot within the 0.9 field of view (27°) is smaller than the Airy disk radius, and the imaging quality of the far-infrared optical system 100 is better.

[0155] Example 3

[0156] Figure 8 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 3. Figure 8 The mid-to-far infrared optical system 100 includes, in order from the object plane A to the image plane B along the optical axis S: an aperture 3, a metalens 1, a refractive lens 2, and a protective member 4, wherein the aperture 3 is located on the side of the metalens 1 close to the object side, that is, there is a preset distance between the aperture 3 and the metalens 1, and the metalens 1 has and only has a rear surface provided with a micro-nano structure 12. The parameters of the far-infrared optical system 100 provided in Example 3 are shown in Table 8.

[0157] Table 8. Partial parameters of various systems of the far-infrared optical system 100 provided in Example 3

[0158] parameter data System volume (TTL) 10.28mm Field of view (2ω) 61.6° F-number 1.0 Equivalent focal length 3.66mm Working band 8-12um

[0159] As can be seen from Table 8, the total optical length of the far-infrared optical system 100 is 10.28 mm, which is less than 14 mm. Therefore, the total optical length of the far-infrared optical system 100 meets the target requirements. The maximum field angle of the far-infrared optical system 100 is 61.6 degrees, which is between 59.752 degrees and 63.448 degrees. Therefore, the maximum field angle of the far-infrared optical system 100 meets the target requirements. The F number of the far-infrared optical system 100 is 1.0. Therefore, the F number of the far-infrared optical system 100 meets the target requirements.

[0160] Along the direction of the optical axis S from the image plane B to the object plane A, each surface in the far-infrared optical system 100 is numbered starting from the object plane A, and the parameters of each surface are summarized to obtain the following Table 9.

[0161] Table 9. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 3

[0162]

[0163] The analysis of each surface in Table 9 can refer to Example 1 and will not be repeated here.

[0164] Surface 5 and surface 6 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0165]

[0166] 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 SS; c is the surface 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, E, F, G, etc. of surface 5 and surface 6 can be obtained from Table 10.

[0167] Table 10. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 3

[0168]

[0169] The method for querying the specific parameters of surface 4 and surface 5 through Table 10 can be referred to Example 1, which will not be repeated here.

[0170] See also Fig. 9 , Fig. 9 FIG. 1 shows the MTF curve of the far-infrared optical system 100 provided in Example 3. Fig. 9 The horizontal axis in is the Y-axis field of view, and its unit is degree. Fig. 9 The vertical axis in is the MTF value. Fig. 9The MTF of 10.5lp / mm spatial frequency is listed as the sagittal image curve S2 and the meridional image curve T2 with the change of field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal image curve S3 and the meridional image curve T3 with the change of field of view, the MTF of 31.5lp / mm spatial frequency is listed as the sagittal image curve S4 and the meridional image curve T4 with the change of field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal image curve S5 and the meridional image curve T5 with the change of field of view. Fig. 9 It can be seen that the MTF value of the far-infrared optical system 100 within the 0.9 field of view (27.54°) is greater than 0.2, and the MTF value of the far-infrared optical system 100 within the 0.8 field of view (24.48°) is greater than 0.3. Therefore, the far-infrared optical system 100 has a good overall picture resolution. In addition, the sagittal curve and the meridian curve at each spatial frequency are not much different, indicating that the far-infrared optical system 100 has good astigmatism control. The MTF value of the far-infrared optical system 100 at 0 field of view (0°, i.e., the center of the picture) and the MTF value at 1 field of view (30.8°) are not much different, indicating that the far-infrared optical system 100 has good field curvature control, indicating that the far-infrared optical system 100 has good overall imaging quality.

[0171] See also Fig.10 , Fig.10 The point diagram of the far-infrared optical system 100 provided in Example 3 is shown. Fig.10 It can be seen that the Airy disk radius of the far-infrared optical system 100 provided in Example 3 is 12.83 μm, and the RMS radius (root mean square error radius) of the light spot within the 0.6 field of view (18.28°) is smaller than the Airy disk radius, and the imaging quality of the far-infrared optical system 100 is better.

[0172] Example 4

[0173] Fig.11 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 4. Fig.11 The mid-to-far infrared optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, a metalens 1, an aperture 3, a refractive lens 2, and a protective member 4, wherein the aperture 3 is located on the surface of the metalens 1 close to the image side, and the front and rear surfaces of the metalens 1 are provided with a micro-nano structure 12. The parameters of the far-infrared optical system 100 provided in Example 4 are shown in Table 11.

[0174] Table 11. Partial parameters of various systems of the far-infrared optical system 100 provided in Example 4

[0175] parameter data System volume (TTL) 10.12mm Field of view (2ω) 61.6° F-number 1.0 Equivalent focal length 3.6mm Working band 8-12um

[0176] As can be seen from Table 11, the total optical length of the far-infrared optical system 100 is 10.12 mm, which is less than 14 mm. Therefore, the total optical length of the far-infrared optical system 100 meets the target requirements. The maximum field angle of the far-infrared optical system 100 is 61.6 degrees, which is between 59.752 degrees and 63.448 degrees. Therefore, the maximum field angle of the far-infrared optical system 100 meets the target requirements. The F number of the far-infrared optical system 100 is 1.0. Therefore, the F number of the far-infrared optical system 100 meets the target requirements.

[0177] Along the direction of the optical axis S from the image plane B to the object plane A, each surface in the far-infrared optical system 100 is numbered starting from the object plane A, and the parameters of each surface are summarized to obtain the following Table 12.

[0178] Table 12. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 4

[0179]

[0180] The analysis of each surface in Table 12 can refer to Example 1 and will not be repeated here.

[0181] Surface 4 and surface 5 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0182]

[0183] 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 SS; 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, E, F, G, etc. of surface 4 and surface 5 can be obtained from Table 13.

[0184] Table 13. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 4

[0185]

[0186] The method for querying the specific parameters of surface 4 and surface 5 through Table 13 can be referred to Example 1, which will not be repeated here.

[0187] See also Fig.12 , Fig.12 FIG. 4 shows the MTF curve of the far-infrared optical system 100 provided in Example 4. Fig.12 The horizontal axis in is the Y-axis field of view, and its unit is degree. Fig.12 The vertical axis in is the MTF value. Fig.12The MTF of 10.5lp / mm spatial frequency is listed as the sagittal image curve S2 and the meridional image curve T2 with the change of field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal image curve S3 and the meridional image curve T3 with the change of field of view, the MTF of 31.5lp / mm spatial frequency is listed as the sagittal image curve S4 and the meridional image curve T4 with the change of field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal image curve S5 and the meridional image curve T5 with the change of field of view. Fig.12 It can be seen that the MTF value of the far-infrared optical system 100 in the whole field of view is greater than 0.2, and the MTF value in the 0.8 field of view (24.64°) is greater than 0.3. Therefore, the far-infrared optical system 100 has good overall image resolution. In addition, the sagittal curve and the meridian curve at each spatial frequency are not much different, indicating that the far-infrared optical system 100 has good astigmatism control. The MTF value of the far-infrared optical system 100 at 0 field of view (0°, i.e., the center of the picture) and the MTF value at 1 field of view (30.8°) are not much different, indicating that the far-infrared optical system 100 has good field curvature control, indicating that the far-infrared optical system 100 has good overall imaging quality.

[0188] See also Fig.13 , Fig.13 The point diagram of the far-infrared optical system 100 provided in Example 4 is shown. Fig.13 It can be seen that the Airy disk radius of the far-infrared optical system 100 provided in Example 4 is 12.33 μm, and the RMS radius (root mean square error radius) of the light spot in the entire field of view is smaller than the Airy disk radius, and the imaging quality of the far-infrared optical system 100 is better.

[0189] See also Fig.14 , Fig.14 A phase distribution diagram of the front surface of the metalens 1 is provided, wherein the phase gradient inflection point P is located on the surface, and the distance between the phase gradient inflection point P and the center of the metalens 1 is 0.74 mm. Fig.15 , Fig.15 The phase distribution diagram of the rear surface of the metalens 1 is provided.

[0190] After summarizing the various parameters of the far-infrared optical system 100 provided by the above four embodiments, the following Table 14 is obtained. Table 14 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.

[0191] Table 14. Parameters of the far-infrared optical system 100 provided in various embodiments

[0192]

[0193]

[0194] See also Fig.16 The present application also provides a far-infrared optical lens 1000, which includes an imaging detector (not shown) and the above-mentioned far-infrared optical system 100. The imaging detector is arranged on the image plane B of the far-infrared optical system 100, and the imaging detector includes but is not limited to CMOS (Complementary Metal Oxide Semiconductor, referred to as CMOS, complementary metal oxide semiconductor) and CCD (Charge Coupled Device, referred to as CCD, charge coupled device).

[0195] See also Fig.16 , the far-infrared optical lens 1000 also includes a lens barrel 200 and a spacer 300. The lens barrel 200 is generally cylindrical, and is provided with a mounting through hole 2001. The mounting through hole 2001 includes a first hole segment 2001a and a second hole segment 2001b along the optical axis S from the object side to the image side, and the first hole segment 2001a and the second hole segment 2001b are connected to each other. The diameter of the first hole segment 2001a is greater than the diameter of the second hole segment 2001b, so the first hole segment 2001a and the second hole segment 2001b together form a step structure, the diameter of the refractive lens 2 is adapted to the diameter of the first hole segment 2001a, and the refractive lens 2 is accommodated in the second hole segment 2001b, and the step structure can prevent it from moving toward the side away from the super lens 1.

[0196] The superlens 1 is received in the first hole section 2001a, and the superlens 1 abuts against the refractive lens 2. The spacer 300 is cylindrical, received in the first hole section 2001a, located on the side of the superlens 1 away from the refractive lens 2, and abuts against the superlens 1 to fix the superlens 1.

[0197] Please refer again Fig.16 The far-infrared optical lens 1000 further includes a pressing ring 400, which is cylindrical and received in the first hole section 2001a. The pressing ring 400 is located on the side of the spacer 300 away from the metalens 1. The pressing ring 400 is connected to the lens barrel 200, and the pressing ring 400 abuts against the spacer 300 to fix the metalens 1 and the refractive lens 2. The connection method between the pressing ring 400 and the lens barrel 200 includes, but is not limited to, threaded connection and bonding.

[0198] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the utility model disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. A far-infrared optical system, characterized in that: The far-infrared optical system comprises: a super lens and a refractive lens in sequence from the object side to the image side along the optical axis; the refractive lens is a positive lens, the surface of the refractive lens close to the object side is convex to the image side, and the surface of the refractive lens close to the image side is convex to the image side; the super lens is a positive lens, the super lens comprises a substrate and a micro-nano structure, and the micro-nano structure is provided on at least one side of the substrate along the optical axis from the object side to the image side; Wherein, the far-infrared optical system satisfies: Wherein, V2 is the Abbe number of the refractive lens, and V m is the Abbe number of the superlens.

2. The far-infrared optical system according to claim 1, characterized in that: The refractive lens is an aspherical lens.

3. The far-infrared optical system according to claim 2, characterized in that: The far-infrared optical system meets the following requirements: Wherein, Φ2 is the focal length of the refractive lens, and Φ m is the optical power of the metalens.

4. The far-infrared optical system according to claim 2, characterized in that: The micro-nano structure is disposed on one and only one of the two side surfaces of the substrate along the optical axis from the object side to the image side, and the far-infrared optical system satisfies:

5. The far-infrared optical system according to claim 2, characterized in that: The micro-nano structure is disposed on both sides of the substrate along the optical axis from the object side to the image side, and the far-infrared optical system satisfies:

6. The far-infrared optical system according to claim 2, characterized in that: The far-infrared optical system meets the following requirements: Wherein, c1 is the curvature of the surface of the refractive lens close to the object side, c2 is the curvature of the surface of the refractive lens close to the image side, and T is the thickness of the refractive lens on the optical axis.

7. The far-infrared optical system according to claim 2, characterized in that: The far-infrared optical system meets the following requirements: Wherein, the r2 is half of the effective aperture of the refractive lens, and the BFL is the optical back focal length of the optical system.

8. The far-infrared optical system according to claim 2, characterized in that: The micro-nano structure is disposed on both sides of the substrate along the optical axis from the object side to the image side. The surface of the superlens close to the object side is the front surface of the superlens, and the surface of the superlens close to the image side is the rear surface of the superlens. The front surface of the superlens or the rear surface of the superlens has a phase gradient inflection point, and the superlens satisfies: Wherein, L is the distance from the phase gradient inflection point to the center of the superlens, and r m It is half of the effective aperture of the superlens.

9. The far-infrared optical system according to claim 1, characterized in that: The micro-nano structure is disposed on two side surfaces of the substrate along the optical axis from the object side to the image side, and the refractive lens is a spherical lens or an aspherical lens.

10. The far-infrared optical system according to any one of claims 1 to 9, characterized in that: The far-infrared optical system further comprises an aperture, which is arranged on a side of the superlens close to the object side; or, The aperture is arranged on the surface of the super lens close to the object side; or, The aperture is disposed between the super lens and the refractive lens; or, The aperture is arranged on the surface of the refractive lens close to the image side; or, The aperture is arranged on a side of the refractive lens close to the image side.

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

12. The far-infrared optical lens according to claim 11, characterized in that: The far-infrared optical lens also includes a lens barrel and a spacer, the lens barrel is provided with a mounting through hole, the mounting through hole includes a first hole section and a second hole section along the optical axis from the object side to the image side, the diameter of the first hole section is greater than the diameter of the second hole section; the refractive lens is accommodated in the second hole section, the super lens is accommodated in the first hole section, and the super lens is abutted against the refractive lens; the spacer is accommodated in the first hole section, the spacer is located on the side of the super lens away from the refractive lens, and the spacer is abutted against the super lens.

13. The far-infrared optical lens according to claim 12, characterized in that: The far-infrared optical lens also includes a pressing ring, which is accommodated in the first hole section, located on a side of the spacer away from the super lens, connected to the lens barrel, and abutted against the spacer.

Images