Optical system and optical lens

Abstract

The application provides an optical system and an optical lens, which sequentially comprise, from an object plane of the optical system to an image plane of the optical system, a first chalcogenide refractive lens, a super lens and a second chalcogenide refractive lens; the first chalcogenide refractive lens and the second chalcogenide refractive lens are both even aspheric lenses; the first chalcogenide refractive lens is in a meniscus shape protruding towards the object plane; a first surface of the second chalcogenide refractive lens facing the object plane and a second surface of the second chalcogenide refractive lens facing the image plane both contain a concave point; the optical power of the first chalcogenide refractive lens, the optical power of the super lens and the optical power of the second chalcogenide refractive lens are all positive optical powers. The application improves the design freedom of the optical system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lenses, and particularly to an optical system and an optical lens. BACKGROUND

[0002] Compared with an optical system operating in a visible light waveband, an optical system operating in a far infrared waveband is more suitable for working environments such as rain, fog, snow, and the like. In the related art, for an optical system operating in a far infrared waveband, in order to enable each lens to provide a phase required by the optical system and to achieve passive athermalization of the optical system, special consideration needs to be given to the positive or negative focal power distribution between different lenses, and there is a defect of low design freedom. SUMMARY

[0003] It is an object of the present application to provide an optical system and an optical lens, without special consideration of the positive or negative focal power distribution between different lenses, the phase provided by each lens can ensure that the optical system has good imaging quality, and passive athermalization of the optical system is achieved, thereby improving the design freedom of the optical system.

[0004] According to an aspect of an embodiment of the present application, an optical system is disclosed, which comprises, in order from an object plane of the optical system to an image plane of the optical system, a first chalcogenide refractive lens, a superlens, and a second chalcogenide refractive lens.

[0005] The first chalcogenide refractive lens and the second chalcogenide refractive lens are both even aspheric lenses; the first chalcogenide refractive lens has a meniscus shape protruding towards the object plane; and the first surface of the second chalcogenide refractive lens facing the object plane and the second surface of the second chalcogenide refractive lens facing the image plane each contain a point of inflection.

[0006] The focal power of the first chalcogenide refractive lens, the focal power of the superlens, and the focal power of the second chalcogenide refractive lens are all positive focal powers.

[0007] In an exemplary embodiment of the present application, the optical system satisfies the following conditions:

[0008] 0.95 < f / epd < 1.05

[0009] wherein f is an effective focal length of the optical system, and epd is an entrance pupil diameter of the optical system. In an exemplary embodiment of the present application, the optical system satisfies the following conditions:

[0010] 0.38 < BFL / f < 0.4

[0011] 0.29 < BFL / TTL < 0.3

[0012] wherein BFL is an optical back focal length of the optical system, f is an effective focal length of the optical system, and TTL is an optical total track length of the optical system.

[0013] In an example embodiment of the present application, the optical system satisfies the following conditions:

[0014]

[0015] wherein f is an effective focal length of the optical system, R1 is a radius of curvature of a first surface of the first chalcogenide refractive lens facing the object plane, D1 is an effective radius of the first surface of the first chalcogenide refractive lens, R5 is a radius of curvature of a first surface of the second chalcogenide refractive lens, D5 is an effective radius of the first surface of the second chalcogenide refractive lens, TTL is an optical total track length of the optical system, and BFL is an optical back focal length of the optical system.

[0016] In an example embodiment of the present application, the optical system satisfies the following conditions:

[0017] 2.3 < f * (n - 1) / (FNO * R1) < 2.5

[0018] wherein f is an effective focal length of the optical system, n is a refractive index of the first chalcogenide refractive lens, FNO is an F-number of the optical system, and R1 is a radius of curvature of a first surface of the first chalcogenide refractive lens facing the object plane.

[0019] In an example embodiment of the present application, the optical system satisfies the following conditions:

[0020] 1.06 < R2 / R1 < 1.09

[0021] wherein R1 is a radius of curvature of a first surface of the first chalcogenide refractive lens facing the object plane, and R2 is a radius of curvature of a second surface of the first chalcogenide refractive lens facing the image plane.

[0022] In an example embodiment of the present application, the optical system satisfies the following conditions:

[0023] 3.4 < sag 21 / sag 22 < 15.1

[0024] wherein sag 21 is a sag of the first surface of the second chalcogenide refractive lens at its maximum radius, and sag 22 is a sag of the second surface of the second chalcogenide refractive lens at its maximum radius.

[0025] In an example embodiment of the present application, the optical system satisfies the following conditions:

[0026] 1.5 < f1 / f < 1.6

[0027] 1.48 < f2 / f < 1.6

[0028] 0.9 < f1 / f2 < 1.05

[0029] wherein f1 is the focal length of the first chalcogenide refractive lens, f2 is the focal length of the second chalcogenide refractive lens, and f is the effective focal length of the optical system.

[0030] In an exemplary embodiment of the application, the optical system satisfies the following conditions:

[0031] 17 < f M / f < 35.5

[0032] 13 < 2f M / (f1+f2) < 29

[0033] wherein f M is the focal length of the hyperlens, f is the effective focal length of the optical system, f1 is the focal length of the first chalcogenide refractive lens, and f2 is the focal length of the second chalcogenide refractive lens.

[0034] In an exemplary embodiment of the application, the optical system satisfies the following conditions:

[0035]

[0036] wherein is the maximum phase difference provided by the hyperlens, D M is the optical effective radius of the hyperlens.

[0037] In an exemplary embodiment of the application, the optical system satisfies the following conditions:

[0038] 0.1 < |ca1 / ct1-ca2 / ct2| < 0.4

[0039] wherein ca1 is the air separation from the center of the second surface of the first chalcogenide refractive lens towards the image plane, ct1 is the center thickness of the first chalcogenide refractive lens, ca2 is the air separation from the center of the hyperlens to the first surface of the second chalcogenide refractive lens, and ct2 is the center thickness of the second chalcogenide refractive lens.

[0040] In an example embodiment of the present application, the optical system further comprises: a diaphragm adjacent to the first surface of the first chalcogenide refractive lens facing the object plane; the diaphragm is disposed on the first surface of the first chalcogenide refractive lens, or the diaphragm is disposed spaced apart from the first surface of the first chalcogenide refractive lens.

[0041] According to an aspect of the embodiments of the present application, an optical lens is disclosed, the optical lens comprising: a lens barrel, an optical system provided by any one of the above embodiments;

[0042] The inner wall of the lens barrel is sequentially provided with a first platform, a second platform and a third platform from the object plane to the image plane; the first chalcogenide refractive lens is supported at the first platform, the superlens is supported at the second platform, and the second chalcogenide refractive lens is supported at the third platform.

[0043] In an example embodiment of the present application, a first compression ring is used to abut against the first surface of the first chalcogenide refractive lens facing the object plane; a spacer ring is used to abut against the second surface of the first chalcogenide refractive lens facing the image plane, and the spacer ring is used to abut against the first surface of the superlens facing the object plane; a second compression ring is used to abut against the second surface of the second chalcogenide refractive lens.

[0044] The optical system provided by the embodiments of the present application sequentially comprises: a first chalcogenide refractive lens, a superlens and a second chalcogenide refractive lens from the object plane to the image plane. The first chalcogenide refractive lens and the second chalcogenide refractive lens are both even aspheric lenses. The first chalcogenide refractive lens is in the shape of a meniscus convex to the object plane, and the first surface of the second chalcogenide refractive lens facing the object plane and the second surface of the second chalcogenide refractive lens facing the image plane both contain a point of inflection. Since the superlens can flexibly provide the required phase of the optical system, and since the first chalcogenide refractive lens and the second chalcogenide refractive lens introduce positive dispersion to the optical system while the superlens introduces negative dispersion to the optical system, in the embodiments of the present application, there is no need to specially assign specific positive focal power and negative focal power to the first chalcogenide refractive lens, the superlens and the second chalcogenide refractive lens. Assigning positive focal power to the first chalcogenide refractive lens, the superlens and the second chalcogenide refractive lens can make the phase provided by each lens ensure that the optical system has good imaging quality and achieve passive athermalization of the optical system, thereby improving the design freedom of the optical system.

[0045] Other characteristics and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0046] It should be understood that the above general description and the following detailed description are only exemplary and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0047] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

[0048] Figure 1 A layout architecture diagram of an optical system in an embodiment of the present application is shown.

[0049] Figure 2 A layout architecture diagram of an optical lens in an embodiment of the present application is shown.

[0050] Figure 3 A layout architecture diagram of a provided optical system in an embodiment of the present application is shown.

[0051] Figure 4 A curve diagram of MTF of a provided optical system in an embodiment of the present application varying with field of view under normal temperature working environment is shown.

[0052] Figure 5 A curve diagram of MTF of a provided optical system in an embodiment of the present application varying with field of view under -40℃ working environment is shown.

[0053] Figure 6 A curve diagram of MTF of a provided optical system in an embodiment of the present application varying with field of view under 80℃ working environment is shown.

[0054] Figure 7 A field curvature diagram of a provided optical system in an embodiment of the present application is shown.

[0055] Figure 8 A distortion diagram of a provided optical system in an embodiment of the present application is shown.

[0056] Figure 9 A relative illumination diagram of a provided optical system in an embodiment of the present application is shown.

[0057] Figure 10 A sagittal chromatic aberration diagram of a provided optical system in an embodiment of the present application is shown.

[0058] Figure 11 An imaging point column diagram of a provided optical system in an embodiment of the present application under normal temperature working environment is shown.

[0059] Figure 12 A phase curve diagram of a provided optical system in an embodiment of the present application is shown.

[0060] Figure 13 A layout architecture diagram of a provided optical system in an embodiment of the present application is shown.

[0061] Figure 14A curve chart of MTF changing with field of view of the provided optical system in an embodiment of the present application under a normal temperature working environment is shown.

[0062] Figure 15 A curve chart of MTF changing with field of view of the provided optical system in an embodiment of the present application under a-40℃ working environment is shown.

[0063] Figure 16 A curve chart of MTF changing with field of view of the provided optical system in an embodiment of the present application under a 80℃ working environment is shown.

[0064] Figure 17 A field curvature chart of the provided optical system in an embodiment of the present application is shown.

[0065] Figure 18 A distortion chart of the provided optical system in an embodiment of the present application is shown.

[0066] Figure 19 A relative illumination chart of the provided optical system in an embodiment of the present application is shown.

[0067] Figure 20 A sagittal chromatic aberration chart of the provided optical system in an embodiment of the present application is shown.

[0068] Figure 21 An imaging point column chart of the provided optical system in an embodiment of the present application under a normal temperature working environment is shown.

[0069] Figure 22 A phase curve chart of the provided optical system in an embodiment of the present application is shown.

[0070] Figure 23 A layout architecture chart of the provided optical system in an embodiment of the present application is shown.

[0071] Figure 24 A curve chart of MTF changing with field of view of the provided optical system in an embodiment of the present application under a normal temperature working environment is shown.

[0072] Figure 25 A curve chart of MTF changing with field of view of the provided optical system in an embodiment of the present application under a-40℃ working environment is shown.

[0073] Figure 26 A curve chart of MTF changing with field of view of the provided optical system in an embodiment of the present application under a 80℃ working environment is shown.

[0074] Figure 27 A field curvature chart of the provided optical system in an embodiment of the present application is shown.

[0075] Figure 28 A distortion map of the provided optical system in an embodiment of the present application is shown.

[0076] Figure 29 A relative illumination map of the provided optical system in an embodiment of the present application is shown.

[0077] Figure 30 A sagittal chromatic aberration map of the provided optical system in an embodiment of the present application is shown.

[0078] Figure 31 An imaging spot diagram of the provided optical system in an embodiment of the present application under a normal temperature working environment is shown.

[0079] Figure 32 A phase curve map of the provided optical system in an embodiment of the present application is shown.

[0080] Figure 33 A layout architecture map of the provided optical system in an embodiment of the present application is shown.

[0081] Figure 34 A curve map of MTF of the provided optical system in an embodiment of the present application under a normal temperature working environment is shown.

[0082] Figure 35 A curve map of MTF of the provided optical system in an embodiment of the present application under a -40℃ working environment is shown.

[0083] Figure 36 A curve map of MTF of the provided optical system in an embodiment of the present application under a 80℃ working environment is shown.

[0084] Figure 37 A field curvature map of the provided optical system in an embodiment of the present application is shown.

[0085] Figure 38 A distortion map of the provided optical system in an embodiment of the present application is shown.

[0086] Figure 39 A relative illumination map of the provided optical system in an embodiment of the present application is shown.

[0087] Figure 40 A sagittal chromatic aberration map of the provided optical system in an embodiment of the present application is shown.

[0088] Figure 41 An imaging spot diagram of the provided optical system in an embodiment of the present application under a normal temperature working environment is shown.

[0089] Figure 42A phase curve of the provided optical system in an embodiment of the present application is shown.

[0090] Figure 43 A layout architecture diagram of the provided optical system in an embodiment of the present application is shown.

[0091] Figure 44 A curve diagram of MTF of the provided optical system in an embodiment of the present application under a normal temperature working environment with respect to changes in field of view is shown.

[0092] Figure 45 A curve diagram of MTF of the provided optical system in an embodiment of the present application under a -40℃ working environment with respect to changes in field of view is shown.

[0093] Figure 46 A curve diagram of MTF of the provided optical system in an embodiment of the present application under a 80℃ working environment with respect to changes in field of view is shown.

[0094] Figure 47 A field curvature diagram of the provided optical system in an embodiment of the present application is shown.

[0095] Figure 48 A distortion diagram of the provided optical system in an embodiment of the present application is shown.

[0096] Figure 49 A relative illumination diagram of the provided optical system in an embodiment of the present application is shown.

[0097] Figure 50 A sagittal chromatic aberration diagram of the provided optical system in an embodiment of the present application is shown.

[0098] Figure 51 An imaging point column diagram of the provided optical system in an embodiment of the present application under a normal temperature working environment is shown.

[0099] Figure 52 A phase curve of the provided optical system in an embodiment of the present application is shown. BRIEF DESCRIPTION OF DRAWINGS

[0101] 1 - first chalcogenide refractive lens; 2 - superlens; 3 - second chalcogenide refractive lens; 4 - window glass; 5 - image plane; 6 - lens barrel; 7 - first compression ring; 8 - spacer ring; 9 - second compression ring. DETAILED DESCRIPTION

[0102] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations can be implemented in any of various forms, and should not be limited to the examples described herein; rather, examples are provided so that this disclosure will be thorough and complete, and fully convey the scope of example implementations to those skilled in the art. Like reference numerals may be used to refer to like elements throughout. The terminology used in the description presented herein is not intended to limit the scope of example implementations, and the terms "example," "exemplary," and "illustrative" are used as terms of

[0103] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more example implementations. In the following description, numerous specific details are provided to give a thorough understanding of example implementations. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail in order to avoid obscuring aspects of the application.

[0104] In nature, there are very few materials that are transparent in the far infrared waveband, and the price of these materials is relatively high compared to materials that are transparent in the visible waveband or in the near infrared waveband; even if artificial chalcogenide glass materials are selected as the material that is transparent in the far infrared waveband, the price of these materials is still relatively high. Therefore, the material of the lens of an optical system that operates in the far infrared waveband is greatly limited.

[0105] In addition, the refractive index temperature coefficient of a material that is transparent in the far infrared waveband is usually 1 to 2 orders of magnitude higher than the refractive index temperature coefficient of a material that is transparent in the visible waveband or in the near infrared waveband. The refractive index temperature coefficient is mainly used to describe the speed of change of the refractive index of a material with the ambient temperature; the greater the refractive index temperature coefficient, the greater the degree of change of the refractive index of the material under the same degree of change of the ambient temperature, thereby resulting in a more unstable optical system. As can be seen, compared to an optical system that operates in the visible waveband or in the near infrared waveband, an optical system that operates in the far infrared waveband is more difficult but also more in need of passive athermalization design. As described above, the material of the lens of an optical system that operates in the far infrared waveband is greatly limited, and therefore the difficulty of passive athermalization design is further increased for an optical system that operates in the far infrared waveband.

[0106] In the related art, for an optical system operating in the far-infrared waveband, the following scheme is mainly adopted for passive athermalization design: a specific positive focal power is assigned to a part of lenses, and a specific negative focal power is assigned to another part of lenses, so that on the one hand, the phases provided by the lenses can ensure that the optical system has good imaging quality, and on the other hand, the influences caused by the refractive index changes of different lenses in the process of changing with the ambient temperature are offset, thereby realizing passive athermalization.

[0107] Therefore, in order to make the lenses provide the required phase of the optical system and realize passive athermalization of the optical system, the related art needs to specially consider the positive and negative focal power distribution between different lenses, and has the defect of low design freedom.

[0108] In order to overcome the above defects in the related art, the present application provides an optical system, which can make the phases provided by the lenses ensure that the optical system has good imaging quality and realize passive athermalization of the optical system without specially considering the positive and negative focal power distribution between different lenses, thereby improving the design freedom of the optical system.

[0109] The optical system provided by the present application operates in the far-infrared waveband. Figure 1 The layout architecture diagram of the optical system in an embodiment of the present application is shown. Figure 1 In the optical system, the object plane is located Figure 1 on the left side, but since the distance between the object plane and the optical system is indefinite, it is not shown in Figure 1 ; the image plane 5 of the optical system is located Figure 1 on the right side. Referring to Figure 1 , the optical system provided by the present application sequentially includes a first chalcogenide refractive lens 1, a superlens 2 and a second chalcogenide refractive lens 3 from the object plane to the image plane 5.

[0110] In the optical system provided by the present application, the superlens 2 includes a substrate and a superstructure unit on the surface of the substrate, and the vertex and / or center of the superstructure unit is provided with a micro-nano structure; the filling material between the micro-nano structures is air or other transparent material in the working waveband. Under the modulation of the superstructure unit on the light, the superlens 2 can flexibly provide the required phase of the optical system.

[0111] In the optical system provided by the present application, the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 are both even aspheric lenses. The first chalcogenide refractive lens 1 is in the shape of a meniscus convex to the object plane, that is, both the first surface thereof facing the object plane and the second surface thereof facing the image plane 5 are convex to the object plane. Moreover, the first surface of the second chalcogenide refractive lens 3 facing the object plane and the second surface of the second chalcogenide refractive lens 3 facing the image plane 5 both contain a reverse point.

[0112] It should be noted that, since the superlens 2 can flexibly provide the phase required by the optical system, the arrangement of the superlens 2 allows more flexible distribution of the optical power among the first chalcogenide refractive lens 1, the superlens 2 and the second chalcogenide refractive lens 3, and thus the phase provided by each lens can ensure good imaging quality of the optical system.

[0113] In addition, since the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 introduce positive dispersion to the optical system, and the superlens 2 introduces negative dispersion to the optical system, the arrangement of the superlens 2 makes the thermal difference caused by the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 be compensated by the superlens 2, thereby realizing passive athermalization of the optical system.

[0114] Therefore, in the embodiments of the present application, without specifically assigning specific positive optical power and negative optical power to the first chalcogenide refractive lens 1, the superlens 2 and the second chalcogenide refractive lens 3, assigning positive optical power to the first chalcogenide refractive lens 1, the superlens 2 and the second chalcogenide refractive lens 3 can make the phase provided by each lens ensure good imaging quality of the optical system and realize passive athermalization of the optical system, thereby improving the design freedom of the optical system.

[0115] Preferably, in an embodiment, the material of the first chalcogenide refractive lens 1 is the same as the material of the second chalcogenide refractive lens 3, i.e., the refractive index and the Abbe number of the two are the same. By selecting the same material for the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3, the material cost of the optical system can be effectively reduced.

[0116] In an embodiment, the optical system provided by the present application satisfies the following condition:

[0117] 0.95 < f / epd < 1.05

[0118] Wherein, f is the effective focal length of the optical system, and epd is the entrance pupil diameter of the optical system.

[0119] In the embodiment, the condition f / epd describes the aperture number of the optical system, i.e., the F number of the optical system. The F number of the optical system can also be denoted as FNO. As the FNO decreases, the amount of light entering the optical system increases, but at the same time the aberration of the optical system also increases.

[0120] Therefore, by setting the lower limit value of the conditional expression to 0.95, the FNO is prevented from being too small, thereby preventing excessive aberration from being introduced into the optical system, so that the optical system can have good imaging quality; and by setting the upper limit value of the conditional expression to 1.05, the FNO is prevented from being too large, thereby preventing the light intake of the optical system from being too low, so that the energy utilization rate is prevented from being excessively reduced, thereby ensuring good imaging contrast.

[0121] In an embodiment, the optical system provided by the present application satisfies the following condition:

[0122] 0.38 < BFL / f < 0.4

[0123] 0.29 < BFL / TTL < 0.3

[0124] wherein BFL is the optical back focal length of the optical system, f is the effective focal length of the optical system, and TTL is the total track length of the optical system.

[0125] In the embodiment, the optical back focal length, the effective focal length, and the total track length of the optical system are limited within reasonable ranges by the two conditional expressions of BFL / f and BFL / TTL.

[0126] In particular, by setting the lower limit value of the conditional expression of BFL / TTL to 0.29, the optical back focal length is prevented from being too small, thereby preventing interference between structural components that need to be installed in the back focal length region during lens assembly, so that the installation of such structural components is prevented (for example, interference between a shutter and other structural components is prevented, thereby preventing the installation of the shutter); and by setting the upper limit value of the conditional expression to 0.3, the total track length is prevented from being too large due to the optical back focal length being too large, thereby preventing the optical system from being too large in size and weight.

[0127] In an embodiment, the optical system provided by the present application satisfies the following condition:

[0128]

[0129] wherein f is the effective focal length of the optical system, R1 is the radius of curvature of the first surface of the first chalcogenide refractive lens 1 facing the object plane, D1 is the effective radius of the first surface of the first chalcogenide refractive lens 1, R5 is the radius of curvature of the first surface of the second chalcogenide refractive lens 3, D5 is the effective radius of the first surface of the second chalcogenide refractive lens 3, TTL is the total track length of the optical system, and BFL is the optical back focal length of the optical system.

[0130] In the embodiment, by setting The lower limit of the conditional expression is set to -1.5, and the upper limit is set to -1, so that the optical system has excellent imaging quality with only two chalcogenide refractive lenses and one super lens, thereby avoiding the use of a large number of lenses, so that the optical system has excellent imaging quality, small size and low cost.

[0131] In an embodiment, the optical system provided by the present application satisfies the following condition:

[0132] 2.3 < f*(n-1) / (FNO*R1) < 2.5

[0133] wherein f is the effective focal length of the optical system, n is the refractive index of the first chalcogenide refractive lens 1, FNO is the aperture number of the optical system, and R1 is the radius of curvature of the first surface of the first chalcogenide refractive lens 1 toward the object plane.

[0134] In this embodiment, the lower limit of the conditional expression f*(n-1) / (FNO*R1) is set to 2.3, and the upper limit is set to 2.5, so that for an imaging detector with a resolution of 640 pixels*512 pixels and a pixel size of 12μm, the optical system can meet excellent imaging quality.

[0135] In an embodiment, the optical system provided by the present application satisfies the following condition:

[0136] 1.06 < R2 / R1 < 1.09

[0137] wherein R1 is the radius of curvature of the first surface of the first chalcogenide refractive lens 1 toward the object plane, and R2 is the radius of curvature of the second surface of the first chalcogenide refractive lens 1 toward the image plane 5.

[0138] Specifically, when the value of the conditional expression R2 / R1 is small, it means that R2 is small and R1 is large. R2 is small, which means that the second surface of the first chalcogenide refractive lens 1 is curved to a large extent, which will result in a large difficulty in processing the first chalcogenide refractive lens 1.

[0139] When the value of the conditional expression R2 / R1 is large, it means that R2 is large and R1 is small. R2 is large, which means that the second surface of the first chalcogenide refractive lens 1 is curved to a small extent; R1 is small, which means that the first surface of the first chalcogenide refractive lens 1 is curved to a large extent. Since the first surface and the second surface of the first chalcogenide refractive lens 1 are both convex to the object plane, when the first surface is curved to a large extent and the second surface is curved to a small extent, the center distance between the first surface and the second surface will be large, which will result in a large thickness of the first chalcogenide refractive lens 1, and further result in a large weight of the optical system.

[0140] Therefore, by setting the lower limit value of the condition formula of R2 / R1 to 1.06, the bending degree of the second surface of the first chalcogenide refractive lens 1 is avoided from being too large, thereby effectively reducing the processing difficulty of the first chalcogenide refractive lens 1; and by setting the upper limit value of the condition formula to 1.09, the thickness of the first chalcogenide refractive lens 1 is avoided from being too large, thereby effectively reducing the weight of the optical system.

[0141] In an embodiment, the optical system provided by the present application satisfies the following conditions:

[0142] 3.4 < sag 21 sag 22 < 15.1

[0143] sag 21 is the sag of the first surface of the second chalcogenide refractive lens 3 at its maximum radius, and sag 22 is the sag of the second surface of the second chalcogenide refractive lens 3 at its maximum radius.

[0144] It should be noted that for the first surface and the second surface of the second chalcogenide refractive lens 3, the greater the sag at the maximum radius, the greater the incident angle of the light at the edge of the corresponding surface, thereby causing greater energy loss of the light at the edge of the corresponding surface, thereby further causing the relative illumination to be significantly reduced at the edge of the imaging image, thereby causing the brightness of the imaging image to be non-uniform.

[0145] Therefore, by setting the lower limit value of the condition formula of sag 21 sag 22 to 3.4 and the upper limit value to 15.1, the sag of the first surface of the second chalcogenide refractive lens 3 at its maximum radius is avoided from being too large, and the sag of the second surface of the second chalcogenide refractive lens 3 at its maximum radius is avoided from being too large, thereby reducing the energy loss of the light at the edge of the corresponding surface, thereby reducing the degree of reduction of the relative illumination at the edge of the imaging image, thereby effectively improving the brightness uniformity of the imaging image.

[0146] In an embodiment, the optical system provided by the present application satisfies the following conditions:

[0147] 1.5 < f1 / f < 1.6

[0148] 1.48 < f2 / f < 1.6

[0149] 0.9 < f1 / f2 < 1.05

[0150] wherein f1 is the focal length of the first chalcogenide refractive lens 1, f2 is the focal length of the second chalcogenide refractive lens 3, and f is the effective focal length of the optical system.

[0151] In this embodiment, the focal lengths of the first chalcogenide refractive lens 1, the second chalcogenide refractive lens 3, and the effective focal length of the optical system are constrained by the three conditional expressions f1 / f, f2 / f, and f1 / f2, thereby controlling the optical power of these three components within a reasonable range and ensuring that the optical system has excellent imaging quality.

[0152] In particular, by setting the lower limit of the conditional expression f1 / f2 to 0.9 and the upper limit to 1.05, the relative symmetry between the first chalcogenide refractive lens 1 and the second chalcogenide refractive lens 3 in the optical system is ensured, thereby effectively reducing the off-axis aberrations of the optical system (mainly including coma and astigmatism), improving the sharpness at the edge of the image, and thus effectively improving the imaging quality of the optical system.

[0153] In one embodiment, the optical system provided in this application satisfies the following conditions:

[0154] 17 < f M / f<35.5

[0155] 13 < 2f M / (f1+f2)<29

[0156] Among them, f M f is the focal length of the superlens 2, f is the effective focal length of the optical system, f1 is the focal length of the first chalcogenide refractive lens 1, and f2 is the focal length of the second chalcogenide refractive lens 3.

[0157] In this embodiment, f M / f and 2f M The two conditional expressions / (f1+f2) are mainly used to jointly constrain the focal length of the superlens 2 and the focal lengths / effective focal lengths of other system components different from the superlens 2. This controls the optical power allocated to the superlens 2 and the optical power allocated to other system components within a reasonable range, thus balancing the overall optical length of the optical system and the imaging quality. In this embodiment, the other system components different from the superlens 2 include: the optical system itself; the first chalcogenide refractive lens 1; and the second chalcogenide refractive lens 3.

[0158] In particular, by setting the lower limit of this conditional expression to 13 and the upper limit to 29, it is beneficial to reduce the total optical length while ensuring the rationality of the lens position distribution to reduce the aberration of the optical system. This is beneficial to balance the total optical length of the optical system and the imaging quality.

[0159] In one embodiment, the optical system provided in this application satisfies the following conditions:

[0160]

[0161] in, the maximum phase difference provided by the superlens 2, in radian rad. M D is the optical effective radius of the superlens 2, in mm.

[0162] Specifically, This conditional expression describes the maximum phase difference of the superlens 2 within its optical effective radius, which reflects the average phase gradient of the superlens 2 to some extent. It should be noted that if the average phase gradient is too small, the chromatic aberration correction capability of the superlens 2 will be too small, which will make it difficult for the superlens 2 to fully correct the chromatic aberration of the optical system; if the average phase gradient is too large, it will require the micro-nano structure to have a very high phase providing capability, but at the same time the phase providing capability of the micro-nano structure has an upper limit, which will result in that the selected micro-nano structure cannot match the target requirement, thereby causing a large matching error.

[0163] Therefore, by setting The lower limit value of this conditional expression is set to 1.7 rad / mm to avoid the average phase gradient being too small, thereby ensuring that the superlens 2 can fully correct the chromatic aberration of the optical system; and the upper limit value of this conditional expression is set to 3.3 rad / mm to avoid the average phase gradient being too large, thereby avoiding a large matching error of the micro-nano structure.

[0164] In an embodiment, the optical system provided by the present application satisfies the following condition:

[0165] 0.1 < |ca1 / ct1-ca2 / ct2| < 0.4

[0166] Wherein, ca1 is the air gap from the center of the second surface of the first chalcogenide refractive lens 1 toward the image plane 5 to the superlens 2, ct1 is the center thickness of the first chalcogenide refractive lens 1, ca2 is the air gap from the superlens 2 to the center of the first surface of the second chalcogenide refractive lens 3, and ct2 is the center thickness of the second chalcogenide refractive lens 3.

[0167] In this embodiment, by setting the lower limit value of this conditional expression to 0.1 and the upper limit value to 0.4, the relative symmetry of the first chalcogenide refractive lens 1, the superlens 2 and the second chalcogenide refractive lens 3 in the optical system is ensured, thereby avoiding the optical system having a large off-axis aberration (mainly including coma and astigmatism), improving the clarity at the edge of the imaging picture, and thereby effectively improving the imaging quality of the optical system.

[0168] In an embodiment, the optical system provided by the present application further comprises: a diaphragm adjacent to the first surface of the first chalcogenide refractive lens 1 toward the object plane; the diaphragm is arranged on the first surface of the first chalcogenide refractive lens 1, or the diaphragm is arranged spaced apart from the first surface of the first chalcogenide refractive lens 1.

[0169] In the embodiment, the diaphragm is mainly used for limiting the light entering range of the optical system. By arranging the diaphragm adjacent to the first surface of the first chalcogenide refractive lens 1, it is beneficial to compress the aperture of the lens (including the super lens and the second chalcogenide refractive lens) located after the first chalcogenide refractive lens 1, thereby further effectively reducing the aperture of the optical system.

[0170] In an embodiment, the optical system provided by the present application further comprises a window glass 4 arranged between the second chalcogenide refractive lens 3 and the image plane 5. The arranged window glass 4 can be used to protect the optical system, so as to improve the structural safety of the optical system; and the window glass 4 can also be used to filter stray light.

[0171] The present application also provides an optical lens, which comprises a lens barrel and the optical system provided by any one of the above embodiments.

[0172] The optical lens provided by the present application is used in the far infrared wave band. Figure 2 The layout architecture of the optical lens in an embodiment of the present application is shown. Referring to FIG. 1, the optical lens comprises a lens barrel 6, an optical system and a window glass 4. Figure 2 In the optical lens provided by the present application, the inner wall of the lens barrel 6 is sequentially provided with a first platform, a second platform and a third platform from the object plane of the optical system to the image plane of the optical system. The first chalcogenide refractive lens 1 is supported at the first platform, the super lens 2 is supported at the second platform, and the second chalcogenide refractive lens 3 is supported at the third platform. In this way, the three platforms are used to fix the lenses in the optical system to the inner wall of the lens barrel.

[0173] In an embodiment, the first chalcogenide refractive lens 1 is abutted by a first pressing ring 7 towards the first surface of the object plane; the second surface of the first chalcogenide refractive lens 1 towards the image plane 5 is abutted by a spacer ring 8, and the first surface of the super lens 2 towards the object plane is also abutted by the spacer ring 8; the second surface of the second chalcogenide refractive lens 3 is abutted by a second pressing ring 9. In this way, the lenses in the optical system are further reinforced under the action of the first pressing ring 7, the spacer ring 8 and the second pressing ring 9.

[0174] It can be understood that, in addition to using the pressing ring and the spacer ring to reinforce the lenses, point gluing can also be used to reinforce the lenses.

[0175] Table 1. Target requirements of various system parameters of the optical system

[0176]

[0177]

[0178] Table 1 shows, in an embodiment, target requirements for each system parameter of the optical system to be provided. Specifically, in an embodiment, the optical system to be provided is targeted to operate in the far-infrared waveband, i.e., the 8-12 pm waveband; the F number target is in the range of 1.0±5%; the relative luminance target at the central wavelength is greater than 95%; the absolute value of the optical distortion target is less than 2%; and the target for the MTF (Modulation Transfer Function) at the 0.8 field of view range for the cutoff frequency of 42 lp / mm (line pairs per millimeter) is greater than or equal to 0.16. The MTF is an important index for describing the imaging quality of an optical system. The closer the MTF value is to the diffraction limit, the better the imaging quality.

[0179] In addition, in the embodiment, the optical system to be provided is targeted to satisfy excellent imaging quality for an imaging detector with a resolution of 640 pixels*512 pixels and a pixel size of 12 pm. It should be noted that if the maximum image circle of the optical system is to be exactly matched with the specifications of the imaging detector, the maximum image circle should be set to 9.84 mm. However, considering that there is a certain assembly error when the optical system is assembled with the imaging detector, in the embodiment, the maximum image circle of the optical system to be provided is set to 10.4 mm, leaving a certain margin for imaging, so as to avoid the occurrence of a blank in a corner of the image when the final imaging is caused by the assembly error.

[0180] With the target requirements shown in Table 1 as the target, the present application exemplarily provides five optical systems satisfying the target requirements shown in Table 1 in five embodiments. Next, the five optical systems provided by the present application will be described in detail.

[0181] Example 1

[0182] Figure 3 A layout architecture diagram of the optical system provided in Embodiment 1 is shown. Referring to Figure 3 The optical system provided in the embodiment includes, in order from the object plane to the image plane, an aperture stop, a first chalcogenide refractive lens, a superlens, a second chalcogenide refractive lens, and a protective glass. The aperture stop is arranged on the first surface of the first chalcogenide refractive lens facing the object plane.

[0183] Each surface in the optical system provided in the embodiment is labeled in the direction from the object plane to the image plane, and the parameters of each surface are summarized to obtain Table 2 as shown below.

[0184] Table 2. Parameters of each surface in the optical system provided in Embodiment 1

[0185]

[0186]

[0187] Wherein, surface 1 is an object surface. Surface 2 is a first surface of the first chalcogenide refractive lens facing the object surface. Surface 3 is a second surface of the first chalcogenide refractive lens facing the image surface. Surface 4 is a first surface of the superlens facing the object surface. Surface 5 is a second surface of the superlens facing the image surface. Surface 6 is a first surface of the second chalcogenide refractive lens facing the object surface. Surface 7 is a second surface of the second chalcogenide refractive lens facing the image surface. Surface 8 is a first surface of the window glass facing the object surface. Surface 9 is a second surface of the window glass facing the image surface. Surface 10 is an image surface.

[0188] As shown in Table 2, surface 1 has an infinite radius of curvature (i.e., it is a plane), the distance between surface 1 and surface 2 is indefinite, and the material between surface 1 and surface 2 is air. Surface 2 is an aspheric surface, is coplanar with the stop, has a radius of curvature of 17.898 mm, a distance of 5.902 mm between surface 2 and surface 3, and a chalcogenide glass as the optical material between surface 2 and surface 3. Surface 3 is an aspheric surface, has a radius of curvature of 19.115 mm, a distance of 8.689 mm between surface 3 and surface 4, and air as the material between surface 3 and surface 4. Surface 4 is a plane, has a distance of 0.300 mm between surface 4 and surface 5, and silicon as the optical material between surface 4 and surface 5. Surface 5 is a plane, has a distance of 5.221 mm between surface 5 and surface 6, and air as the material between surface 5 and surface 6. Surface 6 is an aspheric surface, has a radius of curvature of 20.497 mm, a distance of 3.200 mm between surface 6 and surface 7, and a chalcogenide glass as the material between surface 6 and surface 7. Surface 7 is an aspheric surface, has a radius of curvature of 26.504 mm, a distance of 8.349 mm between surface 7 and surface 8, and air as the material between surface 7 and surface 8. Surface 8 is a plane, has a distance of 1.000 mm between surface 8 and surface 9, and germanium as the material between surface 8 and surface 9. Surface 9 is a plane, has a distance of 0.500 mm between surface 9 and surface 10, and air as the material between surface 9 and surface 10. Surface 10 is a plane.

[0189] For the four aspheric surfaces of surface 2, surface 3, surface 6 and surface 7, the surface shape thereof can be described by the following formula:

[0190]

[0191] Wherein, r represents the radius of a certain position on the lens in the aperture direction, Z(r) represents the sag of a certain position on the lens, c represents the curvature of the lens, k represents the conic constant of the lens, i is an integer greater than or equal to 1, A 2i represents the 2i order coefficient.

[0192] After summarizing the coefficients in the surface shape formula of the four aspheric surfaces, Table 3 shown below is obtained.

[0193] Table 3. Coefficients in the surface shape formulas corresponding to each aspherical surface in Example 1

[0194] Surface No. 2 3 6 7 k -2.707E+00 1.255E-01 0 1.529E+00 [A4] 4.607E-05 -2.546E-05 -6.976E-05 -8.268E-05 [A6] -2.914E-08 -1.508E-08 -2.030E-06 -3.664E-06 [A8] -4.987E-010 -4.802E-10 -3.556E-08 -1.021E-08 A 10 ]]> -6.412E-013 -4.479E-11 6.714E-10 2.904E-10 A 12 ]]> 6.031E-016 3.090E-13 -9.962E-12 -8.744E-13 A 14 ]]> -5.547E-017 -5.865E-16 0 0

[0195] The optical system provided in this embodiment operates in the 8-12μm band; its F-number is 1.01, which is within the target range of 1.0±5%, fully meeting the optical system's requirements for F-number.

[0196] Figure 4 The graph shows the MTF (Mean Transmission Frequency) of the optical system provided in Example 1 as a function of the field of view under normal operating conditions. Normal operating temperature is typically 20°C or 25°C. Figure 4 The horizontal axis represents the field of view measured in image height, in mm; the vertical axis represents the MTF value. Figure 4 In this diagram, T represents the curve along the meridian direction, and S represents the curve along the sagittal direction; the meridian curve T1 and the sagittal curve S1 correspond to a spatial frequency of 10 lp / mm, the meridian curve T2 and the sagittal curve S2 correspond to a spatial frequency of 21 lp / mm, and the meridian curve T3 and the sagittal curve S3 correspond to a cutoff frequency of 42 lp / mm. Furthermore, Figure 4 In the image, 5.2 mm in height corresponds to the full field of view, and 4.16 mm in height corresponds to the 0.8 field of view.

[0197] Depend on Figure 4 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.32, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view under normal operating conditions.

[0198] Figure 5 The graph shows the MTF (Mean Transmission Factor) of the optical system provided in Example 1 as a function of field of view under an operating environment of -40°C. Similarly, for... Figure 4 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 5 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0199] Depend on Figure 5 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.29, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view in an operating environment of -40℃.

[0200] Figure 6 The graph shows the MTF (Mean Transmission Factor) of the optical system provided in Example 1 as a function of field of view under an operating environment of 80°C. Similarly, for... Figure 4The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are not described here again Figure 6 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are not described here again

[0201] From Figure 6 It can be seen that the MTF in the 0.8 field of view range at the cut-off frequency 42.00 lp / mm is always greater than 0.24, that is, always greater than the target specified 0.16, thereby illustrating that the imaging quality of the optical system in the 0.8 field of view range is excellent under the working environment of 80℃.

[0202] In summary Figure 4 to Figure 6 It can be seen that the optical system provided in the embodiment can always maintain excellent imaging quality in the 8-12μm waveband within the temperature range of-40℃-80℃, thereby illustrating that the optical system fully realizes passive athermalization.

[0203] Figure 7 A field curvature graph of the optical system provided in the embodiment 1 is shown. Figure 7 The horizontal axis represents the distance deviation between the actual focal point of the light and the image plane, in mm; and the vertical axis represents the normalized field of view in the positive direction of the Y axis. Figure 7 The field curvature curve T in the meridional direction and the field curvature curve S in the sagittal direction corresponding to the three wavelengths of 8μm, 10μm and 12μm are shown.

[0204] From Figure 7 It can be seen that in the full field of view range at the central wavelength 10μm in the 8-12μm waveband, the field curvature of the optical system in the meridional direction is 0.1494mm, and the field curvature in the sagittal direction is 0.0161mm, thereby illustrating that the field curvature of the optical system is very small.

[0205] Figure 8 A distortion graph of the optical system provided in the embodiment 1 is shown. Figure 8 The horizontal axis represents the distortion degree of imaging, in percentage; and the vertical axis represents the normalized field of view in the positive direction of the Y axis. Figure 8 The distortion curves corresponding to the three wavelengths of 8μm, 10μm and 12μm are shown.

[0206] From Figure 8 It can be seen that the absolute value of the distortion of the optical system at each wavelength in the 8-12μm waveband is less than 1%, that is, less than the target specified 2%, thereby fully meeting the target requirement of the optical system for distortion.

[0207] Figure 9 A relative luminance graph of the optical system provided in the embodiment 1 is shown. Figure 9 The horizontal axis represents the field of view in the image height, in mm; and the vertical axis represents the relative luminance. Figure 9The relative luminance curve at the center wavelength of 10 μm in the working waveband of 8-12 μm is shown.

[0208] The relative luminance curve at the center wavelength of 10 μm in the working waveband of 8-12 μm is shown. Figure 9 It can be seen that the relative luminance of the optical system in the full field of view range at the center wavelength of 10 μm is greater than the target specified 95%, which fully meets the target requirement of the optical system for relative luminance.

[0209] Figure 10 The axial chromatic aberration graph of the optical system provided by embodiment 1 is shown. Figure 10 The horizontal axis represents the deviation amount of the position of the light ray of other wavelengths on the axial image plane compared with the position of the light ray of the center wavelength of the working waveband on the axial image plane, and the unit is μm; the vertical axis represents the field of view in terms of image height, and the unit is mm. Figure 10 Among them, the outermost two curves describe the diameter range of the Airy disk; the remaining three curves are the axial chromatic aberration curves corresponding to the wavelengths of 8 μm, 10 μm and 12 μm respectively, except the outermost two curves.

[0210] The axial chromatic aberration curve at the center wavelength of 10 μm in the working waveband of 8-12 μm is shown. Figure 10 It can be seen that the maximum axial chromatic aberration of the optical system is about 12.2 μm at each wavelength in the waveband of 8-12 μm, which is close to the size of a pixel; the axial chromatic aberration of the optical system is within the diameter range of the Airy disk and has a large margin, which indicates that the chromatic aberration of the optical system has been well compensated.

[0211] Figure 11 The imaging point column graph of the optical system provided by embodiment 1 under the normal temperature working environment is shown. Figure 11 The imaging point column graphs under the wavelengths of 8 μm, 10 μm and 12 μm are shown. Figure 11 Among them, the maximum root mean square radius in the full field of view range is 8.72 μm, which is less than the Airy disk radius of 12.32 μm, which indicates that the optical system fully meets the requirement of clear imaging.

[0212] Figure 12 The phase curve graph of the optical system provided by embodiment 1 is shown. Figure 12 The horizontal axis represents the radius of the corresponding position on the superlens in the aperture direction, and the unit is mm; the vertical axis represents the phase provided by the corresponding position on the superlens, and the unit is 2π rad.

[0213] The phase curve graph of the optical system provided by embodiment 1 is shown. Figure 12 It can be seen that the maximum phase difference of the phase provided by the superlens in the optical system is less than 4.9*2π rad.

[0214] Example 2

[0215] Figure 13A layout architecture diagram of the optical system provided in Embodiment 2 is shown. Referring to Figure 13 The optical system provided in the embodiment comprises, in order from an object plane to an image plane, an aperture stop, a first chalcogenide refractive lens, a superlens, a second chalcogenide refractive lens, and a protective glass. The aperture stop is arranged on a first surface of the first chalcogenide refractive lens facing the object plane.

[0216] The surfaces in the optical system provided in the embodiment are numbered in order from the object plane to the image plane, and the parameters of the surfaces are summarized as shown in Table 4 below.

[0217] Table 4. Parameters of the surfaces in the optical system provided in Embodiment 2

[0218]

[0219]

[0220] The same as the description of Table 2, Table 4 is not described again here.

[0221] The coefficients in the surface type formula corresponding to the surfaces 2, 3, 6, and 7 are summarized as shown in Table 5 below.

[0222] Table 5. Coefficients in the surface type formula corresponding to the aspheric surfaces in Embodiment 2

[0223] Surface No. 2 3 6 7 k -2.829E+00 7.362E-04 0 2.769E+000 [A4] 5.063E-05 -2.057E-05 -6.791E-005 -8.760E-005 [A6] -3.964E-08 -3.593E-08 -2.1101E-006 -3.723E-006 [A8] -5.501E-10 -1.087E-10 -3.412E-008 -6.778E-009 A 10 ]]> 8.259E-13 -4.438E-11 6.665E-010 2.358E-010 A 12 ]]> -5.929E-15 2.815E-13 -1.011E-011 -6.147E-013 A 14 ]]> -4.623E-17 -4.836E-16 0 0

[0224] The optical system provided in the embodiment works in the 8-12 μm waveband; the F number thereof is 1.01, which is within the range of 1.0±5% specified by the target, and fully meets the requirement of the optical system for the F number.

[0225] Figure 14 A curve diagram of the MTF of the optical system provided in Embodiment 2 varying with the field of view in a normal temperature working environment is shown. The same as the description of the meanings represented by the horizontal and vertical axes in Figure 4 and the meanings represented by the curves, which are not described again here. Figure 14 and the meanings represented by the curves.

[0226] From Figure 14 It can be seen that the MTF in the 0.8 field of view range at the cutoff frequency 42.00 lp / mm is always greater than 0.32, i.e., always greater than 0.16 specified by the target, which indicates that the imaging quality of the optical system in the 0.8 field of view range is excellent in the normal temperature working environment.

[0227] Figure 15The curve chart of MTF of the optical system provided in Embodiment 2 changing with field of view under the working environment of -40℃ is shown. The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for Figure 4 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for Figure 15 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for

[0228] It can be seen that the MTF in the range of 0.8 field of view at the cut-off frequency of 42.00 lp / mm is always greater than 0.21, i.e., always greater than the target specified 0.16, thereby indicating that the imaging quality of the optical system in the range of 0.8 field of view under the working environment of -40℃ is excellent. Figure 15

[0229] The curve chart of MTF of the optical system provided in Embodiment 2 changing with field of view under the working environment of 80℃ is shown. The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for Figure 16 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for Figure 4 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for Figure 16 It can be seen that the MTF in the range of 0.8 field of view at the cut-off frequency of 42.00 lp / mm is always greater than 0.24, i.e., always greater than the target specified 0.16, thereby indicating that the imaging quality of the optical system in the range of 0.8 field of view under the working environment of 80℃ is excellent.

[0230] Figure 16 It can be seen that the MTF in the range of 0.8 field of view at the cut-off frequency of 42.00 lp / mm is always greater than 0.24, i.e., always greater than the target specified 0.16, thereby indicating that the imaging quality of the optical system in the range of 0.8 field of view under the working environment of 80℃ is excellent.

[0231] It can be seen that the MTF in the range of 0.8 field of view at the cut-off frequency of 42.00 lp / mm is always greater than 0.24, i.e., always greater than the target specified 0.16, thereby indicating that the imaging quality of the optical system in the range of 0.8 field of view under the working environment of 80℃ is excellent. Figure 14 to Figure 16 It can be seen that the optical system provided in the embodiment can always maintain excellent imaging quality in the wavelength range of 8-12 μm within the temperature range of -40℃-80℃, thereby indicating that the optical system fully realizes passive athermalization.

[0232] Figure 17 The field curvature chart of the optical system provided in Embodiment 2 is shown. The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for Figure 7 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for Figure 17 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for

[0233] It can be seen that, at the center wavelength of 10 μm in the wavelength range of 8-12 μm, the field curvature of the optical system in the meridional direction is 0.1557 mm and the field curvature in the sagittal direction is 0.0133 mm within the full field of view, thereby indicating that the field curvature of the optical system is very small. Figure 17

[0234] The distortion chart of the optical system provided in Embodiment 2 is shown. The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those for Figure 18 Figure 8 ​​The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 18 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0235] Depend on Figure 18 It can be seen that at each wavelength in the 8-12μm band, the absolute value of the distortion of this optical system is less than 1%, which is less than the target specified 2%, fully meeting the target requirements of the optical system for distortion.

[0236] Figure 19 A relative illumination diagram of the optical system provided in Example 2 is shown. Similarly, for... Figure 9 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 19 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0237] Depend on Figure 19 As can be seen, at a center wavelength of 10μm, the relative illumination of this optical system is greater than 95% of the target specified in the entire field of view, which fully meets the target requirements of the optical system for relative illumination.

[0238] Figure 20 A transverse chromatic aberration diagram of the optical system provided in Embodiment 2 is shown. Similarly, for... Figure 10 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 20 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0239] Depend on Figure 20 As can be seen, the maximum transverse chromatic aberration of this optical system is 12.71 μm at each wavelength in the 8–12 μm band, which is close to the size of a pixel. The transverse chromatic aberration of this optical system is all within the Airy disk diameter range and has a large margin, which shows that the chromatic aberration of this optical system has been well compensated.

[0240] Figure 21 An imaging point diagram of the optical system provided in Example 2 under normal operating temperature conditions is shown. Figure 21 The image point arrays at 8μm, 10μm, and 12μm wavelengths are shown. Figure 21 In the full field of view, the maximum root mean square radius is 9.753 μm, which is smaller than the Airy disk radius of 12.35 μm, indicating that the optical system fully meets the requirements for clear imaging.

[0241] Figure 22 A phase curve diagram of the optical system provided in Embodiment 2 is shown. Similarly, for... Figure 12 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 22The meanings represented by the horizontal and vertical axes and the meanings represented by the curves.

[0242] By Figure 22 It can be seen that the maximum phase difference of the phase provided by the superlens in the optical system is less than 4.85*2π rad.

[0243] Example 3

[0244] Figure 23 A layout architecture diagram of the optical system provided in Embodiment 3 is shown. Referring to FIG. 8, the optical system provided in the embodiment comprises, in order from an object plane to an image plane, an aperture stop, a first chalcogenide refractive lens, a superlens, a second chalcogenide refractive lens, and a protective glass. The aperture stop is arranged on a first surface of the first chalcogenide refractive lens facing the object plane. Figure 23

[0245] The surfaces in the optical system provided in the embodiment are labeled in the direction from the object plane to the image plane, and the parameters of the surfaces are summarized as shown in Table 6 below.

[0246] Table 6. Parameters of the surfaces in the optical system provided in Embodiment 3

[0247]

[0248]

[0249] The same as the description for Table 2, Table 6 will not be described here.

[0250] The coefficients in the surface type formulas corresponding to the surfaces 2, 3, 6, and 7 are summarized as shown in Table 7 below.

[0251] Table 7. Coefficients in the surface type formulas corresponding to the aspheric surfaces in Embodiment 3

[0252] Surface No. 2 3 6 7 k -2.978E+00 -8.791E-02 0 -2.841E+00 [A4] 5.236E-05 -8.441E-06 -8.189E-05 -6.853E-05 [A6] -1.054E-07 -2.871E-07 -2.605E-06 -4.110E-06 [A8] -5.018E-10 1.986E-09 -1.670E-08 -1.726E-10 A 10 ]]> 4.641E-12 -3.927E-11 3.133E-10 2.099E-10 A 12 ]]> -3.031E-14 1.889E-13 -7.164E-12 -6.369E-13 A 14 ]]> 1.523E-17 -2.474E-16 0 0

[0253] The optical system provided in the embodiment works in the 8-12 μm waveband; its F number is 1.02, which is within the target specified range of 1.0±5%, and fully meets the requirements of the optical system for the F number.

[0254] Figure 24 A curve diagram of the MTF of the optical system provided in Embodiment 3 varying with the field of view in a normal temperature working environment is shown. The same as the description of the meanings represented by the horizontal and vertical axes and the meanings represented by the curves in Figure 4 the meanings represented by the horizontal and vertical axes and the meanings represented by the curves in Figure 24 the meanings represented by the horizontal and vertical axes and the meanings represented by the curves.

[0255] By​Figure 24 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.27, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view under normal operating conditions.

[0256] Figure 25 The graph shows the MTF (Mean Transmission Factor) of the optical system provided in Example 3 as a function of field of view under an operating environment of -40°C. Similarly, for... Figure 4 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 25 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0257] Depend on Figure 25 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.20, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view in an operating environment of -40℃.

[0258] Figure 26 The graph shows the MTF (Mean Transmission Factor) of the optical system provided in Example 3 as a function of field of view under an operating environment of 80°C. Similarly, for... Figure 4 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 26 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0259] Depend on Figure 26 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.26, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view under the working environment of 80℃.

[0260] comprehensive Figure 24 to Figure 26 As can be seen, the optical system provided in this embodiment can maintain excellent imaging quality in the 8-12μm band within a temperature range of -40℃ to 80℃, which shows that the optical system has fully realized passive calorimetry.

[0261] Figure 27 The field curvature diagram of the optical system provided in Example 3 is shown. Similarly, for... Figure 7 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 27 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0262] Depend on Figure 27It can be seen that, within the 8–12 μm band, at a center wavelength of 10 μm, the field curvature of this optical system is 0.1269 mm in the meridional direction and 0.0140 mm in the sagittal direction, indicating that the field curvature of this optical system is relatively small.

[0263] Figure 28 The distortion diagram of the optical system provided in Embodiment 3 is shown. Similarly, for... Figure 8 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 28 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0264] Depend on Figure 28 It can be seen that at each wavelength in the 8-12μm band, the absolute value of the distortion of this optical system is less than 1%, which is less than the target specified 2%, fully meeting the target requirements of the optical system for distortion.

[0265] Figure 29 A relative illumination diagram of the optical system provided in Example 3 is shown. Similarly, for... Figure 9 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 29 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0266] Depend on Figure 29 As can be seen, at a center wavelength of 10μm, the relative illumination of this optical system is always greater than 97% across the entire field of view, which is always greater than the target specified of 95%, thus fully meeting the target requirements of the optical system for relative illumination.

[0267] Figure 30 A transverse chromatic aberration diagram of the optical system provided in Embodiment 3 is shown. Similarly, for... Figure 10 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 30 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0268] Depend on Figure 30 It can be seen that the maximum transverse chromatic aberration of the optical system is about 14.17 μm at each wavelength in the 8–12 μm band. The transverse chromatic aberration of the optical system is within the range of the Airy disk diameter and has a large margin, which indicates that the chromatic aberration of the optical system has been well compensated.

[0269] Figure 31 An imaging point diagram of the optical system provided in Example 3 under normal operating temperature conditions is shown. Figure 31 The image point diagrams at wavelengths of 8μm, 10μm, and 12μm are shown. Figure 31In the full field of view, the maximum root mean square radius is 13.916 μm, close to the Airy disk radius 12.56 μm, and in the 0.8 field of view, the root mean square radius is less than the Airy disk radius, thus indicating that the optical system basically meets the requirements of clear imaging.

[0270] Figure 32 A phase curve of the optical system provided in Embodiment 3 is shown. The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those described above for Figure 12 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those described above for Figure 32 The meanings represented by the horizontal and vertical axes and the meanings represented by the curves are the same as those described above for

[0271] It can be seen that the maximum phase difference of the phase provided by the superlens in the optical system is less than 3.4*2π rad. Figure 32

[0272] Example 4

[0273] Figure 33 A layout architecture diagram of the optical system provided in Embodiment 4 is shown. Referring to Figure 33 The optical system provided in the embodiment includes, in order from an object plane to an image plane, an aperture stop, a first chalcogenide refractive lens, a superlens, a second chalcogenide refractive lens, and a protective glass. The aperture stop is arranged on a first surface of the first chalcogenide refractive lens facing the object plane.

[0274] The surfaces in the optical system provided in the embodiment are numbered in order from the object plane to the image plane, and the parameters of the surfaces are summarized as shown in Table 8 below.

[0275] Table 8. Parameters of the surfaces in the optical system provided in Embodiment 4

[0276]

[0277]

[0278] The same as the description for Table 2, Table 8 is not described again here.

[0279] The coefficients in the surface type formulas corresponding to the four aspheric surfaces, i.e., surface 2, surface 3, surface 6, and surface 7, are summarized as shown in Table 9 below.

[0280] Table 9. Coefficients in the surface type formulas corresponding to the aspheric surfaces in Embodiment 4

[0281] Surface No. 2 3 6 7 k -3.001E+00 -9.619E-02 0 -2.688E+00 [A4] 5.187E-05 -8.238E-06 -8.197E-05 -6.955E-05 [A6] -1.072E-07 -2.948E-07 -2.594E-06 -4.254E-06 [A8] -4.814E-10 1.990E-09 -1.864E-08 1.474E-09 A 10 ]]> 4.636E-12 -3.902E-11 3.117E-10 2.532E-10 A 12 ]]> -3.189E-14 1.895E-13 -6.762E-12 -1.141E-12 A 14 ]]> 2.274E-17 -2.495E-16 0 0

[0282] ​The optical system provided in this embodiment operates in the 8-12μm band; its F-number is 1.02, which is within the target range of 1.0±5%, fully meeting the optical system's requirements for F-number.

[0283] Figure 34 The graph shows the MTF (Mean Transmission Factor) of the optical system provided in Example 4 as a function of field of view under normal operating conditions. Similarly, for... Figure 4 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 34 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0284] Depend on Figure 34 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.27, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view under normal operating conditions.

[0285] Figure 35 The graph shows the MTF (Mean Transmission Frequency) of the optical system provided in Example 4 as a function of field of view in an operating environment of -40°C. Similarly, for... Figure 4 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 35 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0286] Depend on Figure 35 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.17, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view in an operating environment of -40℃.

[0287] Figure 36 The graph shows the MTF (Mean Transmission Factor) of the optical system provided in Example 4 as a function of field of view under an operating environment of 80°C. Similarly, for... Figure 4 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 36 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0288] Depend on Figure 36 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.17, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view under the working environment of 80℃.

[0289] comprehensive Figure 34 to Figure 36As can be seen, the optical system provided in this embodiment can maintain excellent imaging quality in the 8-12μm band within a temperature range of -40℃ to 80℃, which shows that the optical system has fully realized passive calorimetry.

[0290] Figure 37 The field curvature diagram of the optical system provided in Example 4 is shown. Similarly, for... Figure 7 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 37 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0291] Depend on Figure 37 It can be seen that, within the 8–12 μm band, at a center wavelength of 10 μm, the field curvature of this optical system is 0.0991 mm in the meridional direction and 0.0065 mm in the sagittal direction, indicating that the field curvature of this optical system is very small.

[0292] Figure 38 The distortion diagram of the optical system provided in Embodiment 4 is shown. Similarly, for... Figure 8 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 38 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0293] Depend on Figure 38 It can be seen that at each wavelength in the 8-12μm band, the absolute value of the distortion of this optical system is less than 1%, which is less than the target specified 2%, fully meeting the target requirements of the optical system for distortion.

[0294] Figure 39 A relative illumination diagram of the optical system provided in Example 4 is shown. Similarly, for... Figure 9 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 39 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0295] Depend on Figure 39 As can be seen, at a center wavelength of 10μm, the relative illumination of this optical system is always greater than 97% across the entire field of view, which is always greater than the target specified of 95%, thus fully meeting the target requirements of the optical system for relative illumination.

[0296] Figure 40 A transverse chromatic aberration diagram of the optical system provided in Embodiment 4 is shown. Similarly, for... Figure 10 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 40 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0297] Depend onFigure 40 It can be seen that the maximum sagittal chromatic aberration of the optical system is about 15.18 μm at each wavelength in the 8-12 μm wavelength band; the sagittal chromatic aberration of the optical system is within the range of the Airy disk diameter and has a large margin, thereby indicating that the chromatic aberration of the optical system has been well compensated.

[0298] Figure 41 An imaging spot diagram of the optical system provided in Embodiment 4 under a normal temperature working environment is shown. Figure 41 Imaging spot diagrams under 8 μm wavelength, 10 μm wavelength and 12 μm wavelength are shown. Figure 41 In the full field of view, the maximum root mean square radius is 22.922 μm, which is less than 2 times the Airy disk radius 12.56 μm, thereby indicating that the optical system basically meets the requirements of clear imaging.

[0299] Figure 42 A phase curve diagram of the optical system provided in Embodiment 4 is shown. The meanings represented by the horizontal and vertical axes and the meanings represented by each curve are the same as those described above. Figure 12 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve are the same as those described above. Figure 42 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve are the same as those described above.

[0300] It can be seen that the maximum phase difference of the phase provided by the superlens in the optical system is less than 3.33*2π rad. Figure 42

[0301] Example 5

[0302] A layout architecture diagram of the optical system provided in Embodiment 5 is shown. Referring to FIG. 6, the optical system provided in the embodiment comprises, in order from an object plane to an image plane, a stop, a first chalcogenide refractive lens, a superlens, a second chalcogenide refractive lens and a protective glass. Figure 43 The optical system provided in the embodiment comprises, in order from the object plane to the image plane, the stop, the first chalcogenide refractive lens, the superlens, the second chalcogenide refractive lens and the protective glass. The stop is arranged on a first surface of the first chalcogenide refractive lens facing the object plane. Figure 43 Each surface in the optical system provided in the embodiment is labeled in the direction from the object plane to the image plane, and the parameters of each surface are summarized to obtain Table 10 as shown below.

[0303] Table 10. Parameters of each surface in the optical system provided in Embodiment 5

[0304]

[0305] Surface No. Surface Type Radius of Curvature Thickness Material 1 Object Surface Infinity - - 2 Aspherical (stop) 18.440 mm 5.881 mm Chalcogenide glass 3 Aspherical 20.048 mm 10.223 mm - 4 Spherical Infinity 0.300 mm Silicon 5 Spherical Infinity 4.294 mm - 6 Aspherical 19.675 mm 3.109 mm Chalcogenide glass 7 Aspherical 24.323 mm 8.485 mm - 8 Spherical Infinity 1.000 mm Germanium 9 Spherical Infinity 0.500 mm - 10 Image Surface Infinity - -

[0306] The same as the description of Table 2, Table 10 will not be described here.

[0307] ​After summarizing the coefficients in the surface formulas corresponding to the four aspherical surfaces 2, 3, 6 and 7, we obtain Table 11 as shown below.

[0308] Table 11. Coefficients in the surface shape formulas corresponding to each aspherical surface in Example 5

[0309] Surface No. 2 3 6 7 k -2.972E+00 -9.509E-02 0 -1.957E+00 [A4] 5.196E-05 -8.203E-06 -7.757E-05 -6.508E-05 [A6] -1.081E-07 -2.952E-07 -2.522E-06 -4.305E-06 [A8] -4.849E-10 1.989E-09 -1.961E-08 1.827E-09 A 10 ]]> 4.633E-12 -3.900E-11 3.104E-10 2.619E-10 A 12 ]]> -3.203E-14 1.893E-13 -6.207E-12 -1.187E-12 A 14 ]]> 2.034E-17 -2.516E-16 0 0

[0310] The optical system provided in this embodiment operates in the 8-12μm band; its F-number is 1.02, which is within the target range of 1.0±5%, fully meeting the optical system's requirements for F-number.

[0311] Figure 44 The graph shows the MTF (Mean Transmission Factor) of the optical system provided in Example 5 as a function of field of view under normal operating conditions. Similarly, for... Figure 5 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 44 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0312] Depend on Figure 44 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.25, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view under normal operating conditions.

[0313] Figure 45 The graph shows the MTF (Mean Transmission Frequency) of the optical system provided in Example 5 as a function of field of view in an operating environment of -40°C. Similarly, for... Figure 4 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 45 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0314] Depend on Figure 45 As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.23, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view in an operating environment of -40℃.

[0315] Figure 46 The graph shows the MTF (Mean Transmission Factor) of the optical system provided in Example 5 as a function of field of view under an operating environment of 80°C. Similarly, for... Figure 4 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 46 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0316] Depend on Figure 46As can be seen, the MTF within the 0.8 field of view at the cutoff frequency of 42.00 lp / mm is always greater than 0.24, which is always greater than the target specified 0.16. This indicates that the optical system has excellent imaging quality within the 0.8 field of view under the working environment of 80℃.

[0317] comprehensive Figure 44 to Figure 46 As can be seen, the optical system provided in this embodiment can maintain excellent imaging quality in the 8-12μm band within a temperature range of -40℃ to 80℃, which shows that the optical system has fully realized passive calorimetry.

[0318] Figure 47 The field curvature diagram of the optical system provided in Example 5 is shown. Similarly, for... Figure 7 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 47 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0319] Depend on Figure 47 It can be seen that, within the 8–12 μm band, at a center wavelength of 10 μm, the field curvature of this optical system is 0.0845 mm in the meridional direction and 0.0043 mm in the sagittal direction, indicating that the field curvature of this optical system is very small.

[0320] Figure 48 The distortion diagram of the optical system provided in Embodiment 5 is shown. Similarly, for... Figure 8 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 48 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0321] Depend on Figure 48 It can be seen that at each wavelength in the 8-12μm band, the absolute value of the distortion of this optical system is less than 0.7%, which is less than the target specified 2%, fully meeting the target requirement of the optical system for distortion.

[0322] Figure 49 A relative illumination diagram of the optical system provided in Example 5 is shown. Similarly, for... Figure 9 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 49 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0323] Depend on Figure 49 As can be seen, at a center wavelength of 10μm, the relative illumination of this optical system is always greater than 95% of the target specified in the entire field of view, which fully meets the target requirements of the optical system for relative illumination.

[0324] Figure 50A transverse chromatic aberration diagram of the optical system provided in Embodiment 5 is shown. Similarly, for... Figure 10 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 50 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0325] Depend on Figure 50 It can be seen that the maximum transverse chromatic aberration of the optical system is about 15.89 μm at each wavelength in the 8–12 μm band. The transverse chromatic aberration of the optical system is within the range of the Airy disk diameter and has a large margin, which indicates that the chromatic aberration of the optical system has been well compensated.

[0326] Figure 51 An imaging point diagram of the optical system provided in Example 5 under normal operating temperature conditions is shown. Figure 51 The image point diagrams at wavelengths of 8μm, 10μm, and 12μm are shown. Figure 51 In the full field of view, the maximum root mean square radius is 29.397 μm, which is less than three times the Airy disk radius of 12.73 μm, indicating that the optical system basically meets the requirements for clear imaging.

[0327] Figure 52 A phase curve diagram of the optical system provided in Embodiment 5 is shown. Similarly, for... Figure 12 The meanings of the horizontal and vertical axes, as well as the meanings of each curve, will not be repeated here. Figure 52 The meanings represented by the horizontal and vertical axes and the meanings represented by each curve.

[0328] Depend on Figure 52 It can be seen that the maximum phase difference provided by the superlens in this optical system is less than 2.5*2πrad.

[0329] After summarizing the parameters of the optical systems provided in the above five embodiments, Table 12 is obtained as shown below. Table 12 is mainly used to illustrate that the optical systems provided in this application meet various conditions, all of which have been experimentally verified and supported. Wherein, R2 is the radius of curvature of the second surface of the first chalcogenide refractive lens facing the image plane, and D2 is the effective radius of the second surface of the first chalcogenide refractive lens; R6 is the radius of curvature of the second surface of the second chalcogenide refractive lens facing the image plane, and D6 is the effective radius of the second surface of the second chalcogenide refractive lens.

[0330] Table 12. Parameters of the optical systems provided in each embodiment

[0331]

[0332]

[0333] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

Claims

1. An optical system, characterized in that, The optical system comprises, in sequence from the object plane to the image plane, a first chalcogenide refractive lens, a superlens, and a second chalcogenide refractive lens; the optical system has three lenses with optical power. Both the first chalcogenide refractive lens and the second chalcogenide refractive lens are even-order aspherical lenses; the first chalcogenide refractive lens is convex to the object plane and is meniscus-shaped; the first surface of the second chalcogenide refractive lens facing the object plane and the second surface of the second chalcogenide refractive lens facing the image plane both contain a point of inflection. The optical power of the first chalcogenide refractive lens, the optical power of the superlens, and the optical power of the second chalcogenide refractive lens are all positive optical powers; The optical system satisfies: ； ； in, Let be the focal length of the first chalcogenide refractive lens. The focal length of the second chalcogenide refractive lens is [value missing]. The effective focal length of the optical system is denoted as .

2. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； in, The effective focal length of the optical system is... The entrance pupil diameter of the optical system is denoted as .

3. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； ； in, This is the optical back focal length of the optical system. The effective focal length of the optical system is... The total optical length of the optical system is given.

4. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； in, The effective focal length of the optical system is... Let be the radius of curvature of the first surface of the first chalcogenide refractive lens facing the object plane. Let be the effective radius of the first surface of the first chalcogenide refractive lens. Let be the radius of curvature of the first surface of the second chalcogenide refractive lens. The effective radius of the first surface of the second chalcogenide refractive lens is given. The total optical length of the optical system is given. This is the optical back focal length of the optical system.

5. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； in, The effective focal length of the optical system is... Let be the refractive index of the first chalcogenide refractive lens. The aperture number of the optical system is given. Let be the radius of curvature of the first surface of the first chalcogenide refractive lens facing the object surface.

6. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； in, Let be the radius of curvature of the first surface of the first chalcogenide refractive lens facing the object plane. The radius of curvature of the second surface of the first chalcogenide refractive lens facing the image plane is denoted as .

7. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； in, The sag of the first surface of the second chalcogenide refractive lens at its maximum radius is given. The sag of the second surface of the second chalcogenide refractive lens at its maximum radius is given.

8. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； in, Let be the focal length of the first chalcogenide refractive lens. is the focal length of the second chalcogenide refractive lens.

9. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； ； in, The focal length of the superlens is... The effective focal length of the optical system is... Let be the focal length of the first chalcogenide refractive lens. is the focal length of the second chalcogenide refractive lens.

10. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； in, The maximum phase difference provided by the superlens The effective optical radius of the superlens is given.

11. The optical system according to claim 1, characterized in that, The optical system satisfies the following conditions: ； in, The air gap is the distance from the center of the second surface of the first chalcogenide refractive lens toward the image plane to the superlens. The center thickness of the first chalcogenide refractive lens is given. The air gap is the distance from the superlens to the center of the first surface of the second chalcogenide refractive lens. The center thickness of the second chalcogenide refractive lens is given.

12. The optical system according to claim 1, characterized in that, The optical system further includes: an aperture adjacent to the first surface of the first chalcogenide refractive lens facing the object surface; the aperture is disposed on the first surface of the first chalcogenide refractive lens, or the aperture is spaced apart from the first surface of the first chalcogenide refractive lens.

13. An optical lens, characterized in that, The optical lens includes: a lens barrel and an optical system as described in any one of claims 1-12; From the object plane to the image plane, the inner wall of the lens barrel is provided with a first platform, a second platform and a third platform in sequence; the first chalcogenide refractive lens rests on the first platform, the superlens rests on the second platform and the second chalcogenide refractive lens rests on the third platform.

14. The optical lens according to claim 13, characterized in that, A first pressure ring is used to abut against the first surface of the first chalcogenide refractive lens facing the object plane; a spacer is used to abut against the second surface of the first chalcogenide refractive lens facing the image plane, and the spacer is used to abut against the first surface of the superlens facing the object plane; a second pressure ring is used to abut against the second surface of the second chalcogenide refractive lens.

Images