An optical system and optical lens working in far-infrared wave band

Abstract

The application discloses an optical system and an optical lens working in a far-infrared wave band, which sequentially comprises, from an object side to an image side along an optical axis, a superlens and a spherical lens; the superlens is used for correcting high-order residual aberration; the spherical lens is used for correcting low-order primary aberration; the superlens and the spherical lens are used together for correcting chromatic aberration of the optical system; the absolute value of the curvature radius of the object side surface of the spherical lens is greater than the absolute value of the curvature radius of the image side surface of the spherical lens; the optical system satisfies the following condition: 0.83 <= f / D <= 0.92; wherein f is the effective focal length of the optical system, and D is the entrance pupil diameter of the optical system. The optical system provided in the application can guarantee excellent imaging quality, meet the demand of a large field of view, and significantly reduce the total length of the optical system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lenses, in particular to an optical system and an optical lens working in a far-infrared wave band. BACKGROUND

[0002] Optical systems composed of optical lenses, and optical lenses containing optical systems, are widely used in various fields of life, including but not limited to: the field of photography, the field of smart home, and the field of smart security. The optical systems provided in the related art are usually all composed of traditional refractive lenses. Such optical systems are difficult to simultaneously have a field of view angle, imaging quality, and total optical length. SUMMARY

[0003] In view of the above technical problems, the embodiments of the present application provide an optical system and an optical lens working in a far-infrared wave band. The proposed optical system meets the demand of a large field of view angle while ensuring excellent imaging quality, and significantly reduces the total optical length.

[0004] A first aspect of the embodiments of the present application provides an optical system working in a far-infrared wave band, the optical system comprising, in order from an object side to an image side along an optical axis, a superlens and a spherical lens; the superlens is used to correct high-order residual aberrations; the spherical lens is used to correct low-order primary aberrations; the superlens and the spherical lens are used together to correct chromatic aberration of the optical system; an absolute value of a curvature radius of an object side surface of the spherical lens is greater than an absolute value of a curvature radius of an image side surface of the spherical lens.

[0005] The optical system satisfies the following conditions:

[0006] 0.83≤f / D≤0.92

[0007] Wherein, f is an effective focal length of the optical system, and D is an entrance pupil diameter of the optical system.

[0008] In an exemplary embodiment of the present application, the optical system further satisfies the following conditions:

[0009] 4.2 M Δφ / R M <6.9

[0010] Wherein, f is an effective focal length of the optical system, and D is an entrance pupil diameter of the optical system. M Δφ is a maximum phase difference of a phase provided by the superlens at a single wavelength, and R M is an optically effective radius of the superlens.

[0011] In an exemplary embodiment of the present application, the optical system further satisfies the following conditions:

[0012] 1.0 < r1 / r2 < 2.8

[0013] wherein r1 is a radius of curvature of an object side surface of the spherical lens, and r2 is a radius of curvature of an image side surface of the spherical lens.

[0014] In an exemplary embodiment of the present application, the optical system further satisfies the following condition:

[0015] 0.40 < R M / R G < 0.55

[0016] wherein R M is an optically effective radius of the hyperlens, and R G is an optically effective radius of the spherical lens.

[0017] In an exemplary embodiment of the present application, the optical system further satisfies the following condition:

[0018] 1 < f M < 1.85

[0019] wherein f M is an effective focal length of the hyperlens.

[0020] In an exemplary embodiment of the present application, the optical system further satisfies the following condition:

[0021] 1.25 < f G < 1.75

[0022] wherein f G is an effective focal length of the spherical lens.

[0023] In an exemplary embodiment of the present application, the optical system further satisfies the following condition:

[0024] 3.3 < n M < 4.3

[0025] 3.3 < n G < 4.3

[0026] wherein n M is a refractive index of the hyperlens, and n G is a refractive index of the spherical lens.

[0027] In an exemplary embodiment of the present application, the optical system is further provided with a diaphragm; the diaphragm is arranged on a surface of the hyperlens, or the diaphragm is arranged apart from the hyperlens.

[0028] In an exemplary embodiment of the present application, the hyper surface of the hyperlens is arranged on an image side surface of the hyperlens.

[0029] The second aspect of the embodiments of the present application provides an optical lens working in a far-infrared wave band, the optical lens comprising the optical system shown in any of the above embodiments, and an imaging detector arranged at an image plane.

[0030] In an example embodiment of the present application, a window glass is arranged between the spherical lens and the imaging detector.

[0031] The optical system provided by the present application comprises a superlens and a spherical lens; and the optical system satisfies the following condition: 0.83≤f / D≤0.92, wherein f is an effective focal length of the optical system, and D is an entrance pupil diameter of the optical system. By controlling f / D to be between 0.83 and 0.92, the present application can guarantee excellent imaging quality while meeting the demand for a large field of view; and since the thickness of the superlens is significantly reduced compared with a traditional refractive lens, the optical total length of the optical system comprising the superlens and the spherical lens is significantly reduced compared with the optical system comprising at least two refractive lenses in the related art. Therefore, the optical system provided by the present application can guarantee excellent imaging quality while meeting the demand for a large field of view and significantly reducing the optical total length.

[0032] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and are not limiting to the present application. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The architecture layout schematic diagram of the optical system and the optical lens working in the far-infrared wave band in an embodiment of the present application is shown.

[0034] Figure 2 The architecture layout schematic diagram of the optical system and the optical lens working in the far-infrared wave band in an embodiment of the present application is shown.

[0035] Figure 3 The MTF field curve diagram of the optical system working in the far-infrared wave band in an embodiment of the present application is shown.

[0036] Figure 4 The relative luminance curve diagram of the optical system working in the far-infrared wave band in an embodiment of the present application is shown.

[0037] Figure 5 The spot diagram of the optical system working in the far-infrared wave band in an embodiment of the present application is shown.

[0038] Figure 6 The axial aberration curve of the optical system working in the far-infrared wave band in an embodiment of the present application is shown.

[0039] Figure 7 A vertical chromatic aberration curve of the optical system operating in a far-infrared wave band in an embodiment of the present application is shown.

[0040] Figure 8 A phase distribution diagram of the superlens in an embodiment of the present application is shown.

[0041] Figure 9 An architectural layout schematic diagram of the optical system and the optical lens operating in a far-infrared wave band in an embodiment of the present application is shown.

[0042] Figure 10 An MTF field curve diagram of the optical system operating in a far-infrared wave band in an embodiment of the present application is shown.

[0043] Figure 11 A phase distribution diagram of the superlens in an embodiment of the present application is shown.

[0044] Figure 12 An architectural layout schematic diagram of the optical system and the optical lens operating in a far-infrared wave band in an embodiment of the present application is shown.

[0045] Figure 13 An MTF field curve diagram of the optical system operating in a far-infrared wave band in an embodiment of the present application is shown.

[0046] Figure 14 A phase distribution diagram of the superlens in an embodiment of the present application is shown.

[0047] Figure 15 An architectural layout schematic diagram of the optical system and the optical lens operating in a far-infrared wave band in an embodiment of the present application is shown.

[0048] Figure 16 An MTF field curve diagram of the optical system operating in a far-infrared wave band in an embodiment of the present application is shown.

[0049] Figure 17 A phase distribution diagram of the superlens in an embodiment of the present application is shown.

[0050] Figure 18 An architectural layout schematic diagram of the optical system and the optical lens operating in a far-infrared wave band in an embodiment of the present application is shown.

[0051] Figure 19 An MTF field curve diagram of the optical system operating in a far-infrared wave band in an embodiment of the present application is shown.

[0052] Figure 20 A relative luminance curve diagram of the optical system operating in a far-infrared wave band in an embodiment of the present application is shown.

[0053] Figure 21 A phase distribution diagram of the superlens in an embodiment of the present application is shown.

[0054] Figure 22 An architectural layout diagram of the optical system and optical lens operating in the far-infrared waveband in an embodiment of the present application is shown.

[0055] Figure 23 An MTF field curve diagram of the optical system operating in the far-infrared waveband in an embodiment of the present application is shown.

[0056] Figure 24 A relative illumination curve diagram of the optical system operating in the far-infrared waveband in an embodiment of the present application is shown.

[0057] Figure 25 A phase distribution diagram of the superlens in an embodiment of the present application is shown.

[0058] Figure 26 An architectural layout diagram of the optical system and optical lens operating in the far-infrared waveband in an embodiment of the present application is shown.

[0059] Figure 27 An MTF field curve diagram of the optical system operating in the far-infrared waveband in an embodiment of the present application is shown.

[0060] Figure 28 A relative illumination curve diagram of the optical system operating in the far-infrared waveband in an embodiment of the present application is shown.

[0061] Figure 29 A phase distribution diagram of the superlens in an embodiment of the present application is shown.

[0062] Reference Signs:

[0063] 1 - superlens; 11 - object side surface of the superlens; 12 - image side surface of the superlens; 2 - spherical lens; 21 - object side surface of the spherical lens; 22 - image side surface of the spherical lens; 3 - window glass; 4 - imaging detector. DETAILED DESCRIPTION

[0064] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The description of the exemplary embodiments is intended to apply to all alternative embodiments, as would be understood by persons skilled in the art. The following exemplary embodiments are described herein with reference to the figures. Wherever possible, the same reference numbers are used in the figures to indicate the same or similar elements. The following exemplary embodiments describe implementations potentially applicable to the present application. They are not meant to be all inclusive of all implementations consistent with the present application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of the present application, as detailed in the appended claims.

[0065] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in this application and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or," as used herein, refers to and encompasses any and all possible combinations of one or more of the associated listed items.

[0066] It should be understood that, although the terms first, second, third, etc. can be used herein to describe various information, but the information should not be limited to these terms. These terms are only used to distinguish one type of information from another type of information. For example, without departing from the scope of the application, the first information can also be referred to as the second information, and similarly, the second information can also be referred to as the first information. Depending on the context, the word "if" as used herein can be interpreted as "when" or "upon" or "in response to determining". The features in the following embodiments and implementations can be combined with each other, without conflict.

[0067] In the field of smart home, smart security, etc., "living body sensing in indoor environment" is an important part. For example: in the field of smart home, through the optical lens arranged on furniture or wall, it is sensed whether there is living body in the indoor environment; and then according to the sensing result, the matching program is executed to provide intelligent home service to the household.

[0068] Although the indoor environment is generally stable, there are two cases of night and day. In order to make "living body sensing in indoor environment" adapt to the two cases of night and day, the optical lens can work in the far infrared waveband, i.e. 8-12 μm, so as to sense the living body from the heat source, thereby avoiding the influence of different environments. At the same time, since the indoor environment is usually static, in order to cover the entire indoor environment in the sensing range as much as possible, the field of view FOV of the optical system inside the optical lens needs to be as large as possible, so as to realize the largest sensing range coverage with the least optical lens.

[0069] The optical system inside the optical lens in the related art is usually composed of traditional refractive lenses. In order to have a large field of view while ensuring the imaging quality, the refractive lenses need to be stacked, which leads to a significant increase in the total optical length TTL of the optical system with the increase in the number of refractive lenses. At the same time, the volume and weight of the optical system will also increase significantly. This feature of the related art obviously does not meet the needs of miniaturization and light weight of optical devices in today's society.

[0070] As described above, in the related art, there is a defect that it is difficult for an optical system to simultaneously consider a field angle, imaging quality, and an optical total length. In order to overcome the defect, the present application provides an optical system working in a far-infrared wave band and an optical lens comprising the optical system. The optical system provided by the present application can guarantee excellent imaging quality, meet the requirement of a large field angle, and significantly reduce the optical total length.

[0071] Figure 1 An architectural layout schematic diagram of the optical system working in the far-infrared wave band and the optical lens in an embodiment of the present application is shown. In the Figure 1 , the direction from left to right is the direction from the object side to the image side. Referring to Figure 1 , the optical system provided by the present application comprises a superlens 1 and a spherical lens 2. The superlens 1 and the spherical lens 2 are arranged in sequence along the optical axis from the object side to the image side.

[0072] The superlens 1 is an optical modulator obtained by arranging a super surface on a substrate; the super surface is composed of a plurality of micro-nano structures. According to the phase modulation mode adopted, the phase modulation formula matched can be used to configure the parameters of the micro-nano structures, so that the superlens 1 can achieve corresponding optical performance.

[0073] In the present application, the superlens 1 is mainly used to correct high-order residual aberrations, and at the same time, the spherical lens 2 is mainly used to correct low-order primary aberrations. Generally, the low-order primary aberrations refer to the first-order to second-order aberrations, and the high-order residual aberrations refer to the third-order and subsequent aberrations. Moreover, the superlens 1 and the spherical lens 2 cooperate to correct the chromatic aberration of the optical system.

[0074] In the present application, the spherical lens 2 has two curved surfaces: an object side surface 21 facing the object side and an image side surface 22 facing the image side; both the object side surface 21 and the image side surface 22 are perpendicular to the optical axis. The absolute value of the curvature radius of the object side surface 21 is greater than the absolute value of the curvature radius of the image side surface 22.

[0075] The optical system provided by the present application satisfies the following conditions:

[0076] 0.83≤f / D≤0.92

[0077] Wherein, f is the effective focal length of the optical system, and D is the entrance pupil diameter of the optical system.

[0078] Specifically, f / D is the aperture number of the optical system, also known as F number, which is mainly used to control the light amount of the optical system. It should be noted that f / D cannot be too large, otherwise the light amount will be small, the utilization rate of light energy will be low, and the imaging quality will be poor. At the same time, f / D cannot be too small, otherwise the overall aberration of the optical system will be large, which will also lead to poor imaging quality. The present inventors have found that by controlling f / D to be between 0.83 and 0.92, the field of view FOV can meet the requirement of 100°≤FOV≤120° while ensuring excellent imaging quality.

[0079] It should be further noted that the thickness of the superlens 1 is significantly reduced compared to the conventional refractive lens. Therefore, compared to the optical system in the related art which is composed of at least two refractive lenses, the optical total length of the optical system provided in the present application, which includes the superlens 1 and the spherical lens 2, is significantly reduced. As can be seen, the optical system provided in the present application meets the requirement of large field of view while ensuring excellent imaging quality and significantly reducing the optical total length.

[0080] In an embodiment, the optical system provided in the present application also meets the following condition:

[0081] 4.2 < f / D < 6.9 M Δφ / R M < 6.9

[0082] wherein f is the effective focal length of the superlens, Δφ is the maximum phase difference of the phase provided by the superlens at a single wavelength, R M is the optical effective radius of the superlens. M

[0083] Specifically, the single wavelength in the present embodiment refers to a single wavelength in the far infrared band. At the single wavelength, the phase provided by different positions of the superlens is generally different. In the present embodiment, the relationship between the effective focal length of the superlens, the maximum phase difference of the superlens, and the optical effective radius of the optical system is constrained by the condition, so that the superlens has excellent phase matching effect, the optical performance of the superlens is more fully played, and the processing difficulty of the superlens can be effectively reduced and the usability of the superlens can be increased.

[0084] In an embodiment, the optical system provided in the present application also meets the following condition:

[0085] 1.0 < r1 / r2 < 2.8

[0086] wherein r1 is the curvature radius of the object side surface 21 of the spherical lens 2, and r2 is the curvature radius of the image side surface 22 of the spherical lens 2.

[0087] ​It should be noted that |r1| should be greater than |r2| to ensure that the spherical lens 2 can provide sufficient optical power; however, if r1 / r2 is too large, the angle of the light beam incident on the image plane from the spherical lens 2 will be too large, thereby resulting in excessive aberration. Therefore, in the embodiment, the lower limit value of r1 / r2 is configured to be 1.0, so that the spherical lens 2 provides sufficient optical power in the optical system provided by the present application, effectively focuses the light beam on the image plane, and ensures that the relative luminance can always be maintained at a high level. Moreover, the upper limit value of r1 / r2 is configured to be 2.8, which, while improving the relative luminance, also restricts the size of the aberration generated by the spherical lens 2, thereby avoiding excessive aberration.

[0088] In an embodiment, the optical system provided by the present application also satisfies the following condition:

[0089] 0.40≤R M / R G ≤0.55

[0090] wherein R M is the optical effective radius of the superlens 1, and R G is the optical effective radius of the spherical lens 2.

[0091] It should be noted that in the optical system provided by the present application, the ratio of the optical effective radii between the superlens 1 and the spherical lens 2, R M / R G , will directly affect the aperture of the optical system. Therefore, in the embodiment, R M / R G is limited to between 0.40 and 0.55 to restrict the aperture of the optical system, thereby enabling the volume of the optical system to be as small as possible.

[0092] In an embodiment, the optical system provided by the present application also satisfies the following condition:

[0093] 1<f M / f≤1.85

[0094] wherein f M is the effective focal length of the superlens 1.

[0095] It should be noted that in the optical system provided by the present application, the greater the optical power provided by the superlens 1 in the optical system, the greater the chromatic dispersion that will be brought to the optical system; moreover, the optical power provided by the superlens 1 in the optical system should be less than the system focal length, to facilitate the micro-nano structure in the superlens 1 to match the required target phase. Therefore, in the embodiment, f MThe lower limit value of f is configured as 1, so that the optical power provided by the superlens 1 in the optical system is less than the system optical power, to facilitate the micro-nano structure to match the required target phase, and to avoid the superlens 1 providing too large optical power in the optical system, thereby avoiding too large chromatic dispersion of the optical system.

[0096] In the embodiment, f is configured as 1.25, and f is configured as 1.75. M The upper limit value of f is configured as 1.85, to ensure that the superlens 1 has certain optical power to complete light modulation within the system length of the optical system provided in the application.

[0097] In an embodiment, the optical system provided in the application also satisfies the following conditions:

[0098] 1.25≤f G / f≤1.75

[0099] Wherein, f is the effective focal length of the spherical lens 2. G

[0100] It should be noted that in the optical system provided in the application, the thickness of the spherical lens 2 will be significantly affected by the optical power provided by the spherical lens 2 in the optical system: as the optical power provided by the spherical lens 2 in the optical system increases, the thickness of the spherical lens 2 significantly increases. Therefore, in the embodiment, f is configured as 1.25, and f is configured as 1.75. G The lower limit value of f is configured as 1.25, to avoid the spherical lens 2 providing too large optical power, thereby avoiding the thickness of the spherical lens 2 being too large, and further avoiding the total optical length being too long.

[0101] In the embodiment, f is configured as 1.25, and f is configured as 1.75. G The upper limit value of f is configured as 1.75, to avoid the lower limit ability of the optical power provided by the spherical lens 2 being too weak, thereby avoiding the superlens 1 needing to provide too large optical power in some cases; if the superlens 1 needs to provide too large optical power, the superlens 1 will be difficult to make the micro-nano structure match the required target phase, and will bring too large chromatic aberration to the optical system. As can be seen, by configuring the upper limit value of f as 1.75, the final excellent imaging quality is stably ensured. G The upper limit value of f is configured as 1.75, to avoid the lower limit ability of the optical power provided by the spherical lens 2 being too weak, thereby avoiding the superlens 1 needing to provide too large optical power in some cases; if the superlens 1 needs to provide too large optical power, the superlens 1 will be difficult to make the micro-nano structure match the required target phase, and will bring too large chromatic aberration to the optical system. As can be seen, by configuring the upper limit value of f as 1.75, the final excellent imaging quality is stably ensured.

[0102] In an embodiment, the optical system provided in the application also satisfies the following conditions:

[0103] 0.2mm≤d M ≤0.375mm

[0104] Wherein, d is the central thickness of the superlens 1. M

[0105] In an embodiment, the optical system provided in the application also satisfies the following conditions: ​​

[0106] 1.2mm≤d G ≤2.25mm

[0107] wherein, d G is the center thickness of the spherical lens 2.

[0108] It should be noted that in the optical system provided in the present application, the superlens 1 will bring obvious negative dispersion to the optical system, and therefore the spherical lens 2 needs to provide certain positive dispersion to compensate. Therefore, in the present embodiment, the lower limit value of d G is configured as 1.2mm to meet the dispersion balance requirement of the optical system. And the upper limit value of d G is configured as 2.25mm to avoid the thickness of the spherical lens 2 being too large, and further avoid the total optical length being too long.

[0109] In an embodiment, the optical system provided in the present application also meets the following conditions:

[0110] 3.3≤n M ≤4.3

[0111] 3.3≤n G ≤4.3

[0112] wherein, n M is the refractive index of the superlens 1 in the far infrared waveband, and n G is the refractive index of the spherical lens 2 in the far infrared waveband.

[0113] Preferably, considering the transmittance of light in the far infrared waveband and the manufacturing cost, the materials of the superlens 1 and the spherical lens 2 are both intrinsic silicon; that is, n M and n G are both 3.42 at a wavelength of 10μm.

[0114] In an embodiment, the optical system is also provided with a diaphragm; the diaphragm is arranged on the surface of the superlens, or the diaphragm is arranged spaced apart from the superlens.

[0115] In the present embodiment, a diaphragm is arranged in the optical system to control the amount of light entering the optical system. The arranged diaphragm can be arranged on the object side surface of the superlens 1 facing the object side, or on the image side surface of the superlens 1 facing the image side; the arranged diaphragm can also be arranged spaced apart from the superlens 1, but only air exists between the diaphragm and the superlens 1, and no other structural members exist.

[0116] In an embodiment, the metasurface of the superlens is arranged on the image side surface of the superlens.

[0117] In this embodiment, the metasurface of the superlens 1 is arranged on the image side 12 of the superlens 1, that is, the metasurface is arranged inside the optical system, avoiding exposure to the external environment. In this way, the micro-nano structure on the metasurface can be effectively protected.

[0118] The application also provides an optical lens working in a far-infrared wave band, which comprises the optical system shown in any of the above embodiments, and details of the optical system are not described herein again. See Figure 1 The optical lens provided by the application comprises an optical system comprising a superlens 1 and a spherical lens 2, and an imaging detector 4 arranged on an image plane. The light in the far-infrared wave band is modulated by the superlens 1 and the spherical lens 2 in turn, and then received and imaged by the imaging detector 4 on the image plane.

[0119] It should be noted that when the optical lens provided by the application is applied to a living body sensing in an indoor environment, the spatial distance of the indoor environment is usually limited, so in this case, the working distance of the optical lens is usually only a few meters, and therefore a high-resolution imaging detector is not required; a low-resolution imaging detector can also achieve good application results, and can also reduce costs.

[0120] In an embodiment, a window glass 3 is arranged between the spherical lens 2 and the imaging detector 4 in the optical lens provided by the application to protect the optical system and the imaging detector 4.

[0121] In an embodiment, the material of the window glass 3 is silicon.

[0122] Table 1. Target requirements of various system parameters of the optical system

[0123] System parameters Target requirements Working waveband (unit: pm) 8～12 f / D 0.9 Field of view FOV (unit: °) ≥100 Optical total length TTL (unit: mm) ≤5

[0124] Table 1 shows the target requirements of various system parameters for the optical system to be provided in an embodiment. In detail, in an embodiment, the optical system to be provided is targeted to work in a far-infrared wave band, i.e., an 8-12 μm wave band; the target f / D is close to 0.9; the target field of view angle is ≥100°; and the target total optical length is ≤5 mm.

[0125] Taking the target requirements shown in Table 1 as the target, the application exemplarily provides seven optical systems satisfying the target requirements shown in Table 1 in seven embodiments. Next, the seven optical systems provided by the application are described in detail.

[0126] Example 1

[0127] Figure 2The schematic diagram of the architecture layout of the optical system and the optical lens working in the far-infrared wave band in Embodiment 1 is shown. Referring to Figure 2 In Embodiment 1, the optical lens comprises, in order from the object side to the image side along the optical axis, an optical system, a window glass, and an imaging detector; wherein the optical system comprises, in order from the object side to the image side along the optical axis, a diaphragm, a superlens, and a spherical lens; the diaphragm is arranged on the object side of the superlens.

[0128] Table 2. System parameters of the optical system provided in Embodiment 1

[0129] System parameters Optical system provided by Example 1 Effective focal length f of optical system (unit: mm) 1.4926 Entrance pupil diameter D of optical system (unit: mm) 1.756 f / D 0.85 Field of view FOV (unit: °) ≥117 Optical total length TTL (unit: mm) 4.608 Relative illumination >60％

[0130] As can be seen from Table 2, the F number (i.e. f / D) of the optical system in this embodiment is only 0.85, which can greatly improve the light amount of the optical system, and in the case that the imaging detector has a lower response to light energy, the energy entering the optical system is collected as much as possible, thereby ensuring excellent imaging quality; at the same time, the field of view angle of the optical system reaches 117° or above, fully meeting the requirement of the optical system for a large field of view angle; at the same time, the total optical length is only 4.608 mm, fully meeting the requirement of the optical system for miniaturization and thinness; at the same time, the relative illuminance of the full field of view is greater than 60%, basically meeting the requirement of the optical system for imaging brightness.

[0131] According to the direction from the object side to the image side, each surface in the optical system is numbered, and the parameters of each surface are summarized to obtain Table 3 below.

[0132] Table 3. Parameters of each surface of the optical system provided in Embodiment 1

[0133] Surface serial number Surface type Curvature radius (mm) Thickness (mm) Material 1 Object plane Infinite Infinite - 2 (diaphragm) Spherical surface Infinite 0.3 Si 3 Super surface Infinite 0.4988 - 4 Spherical surface -7.2313 1.5971 Si 5 Spherical surface -3.4800 1.4774 - 6 Spherical surface Infinite 0.425 Si 7 Spherical surface Infinite 0.31 - 8 Image plane Infinite - -

[0134] As shown in Table 3, surface 1 is the object plane; the object plane is a spherical plane with an infinite radius of curvature, i.e., the object plane is a plane; the distance between the object plane and the object side surface of the superlens is indefinite, so the distance between the object plane and the object side surface of the superlens is recorded as infinite; the material between the object plane and the object side surface of the superlens is air. Surface 2 is the object side surface of the superlens, which is coplanar with the diaphragm, and is a plane; the distance between the object side surface of the superlens and the image side surface of the superlens is 0.3 mm; the material between the object side surface of the superlens and the image side surface of the superlens is silicon. Surface 3 is the image side surface of the superlens, which is a plane; the distance between the image side surface of the superlens and the object side surface of the spherical lens is 0.4988 mm; the material between the image side surface of the superlens and the object side surface of the spherical lens is air. Surface 4 is the object side surface of the spherical lens, which has a radius of curvature of -7.2313 mm; the distance between the object side surface of the spherical lens and the image side surface of the spherical lens is 1.5971 mm; the material between the object side surface of the spherical lens and the image side surface of the spherical lens is silicon. Surface 5 is the image side surface of the spherical lens, which has a radius of curvature of -3.4800; the distance between the image side surface of the spherical lens and the object side surface of the window glass is 1.4774 mm; the material between the image side surface of the spherical lens and the object side surface of the window glass is air. Surface 6 is the object side surface of the window glass, which is a plane; the distance between the object side surface of the window glass and the image side surface of the window glass is 0.425 mm; the material between the object side surface of the window glass and the image side surface of the window glass is silicon. Surface 7 is the image side surface of the window glass, which is a plane; the distance between the image side surface of the window glass and the image plane is 0.31 mm; the material between the image side surface of the window glass and the image plane is air. Surface 8 is the image plane, which is a plane.

[0135] Figure 3 The MTF field curve of the optical system in Embodiment 1 provided in the present application is shown. MTF (Modulation Transfer Function) is an important index for describing the imaging quality of an optical system. The greater the MTF value, the better the imaging quality. Referring to Figure 3 In the present embodiment, the pixel size in the specification is 35 μm, so the Nyquist frequency n of the optical system is 1000 / (2*35)≈14 lp / mm. Therefore Figure 3 The sagittal image curve S1 and the meridional image curve T1 of the MTF at a spatial frequency of 3.5 lp / mm, the sagittal image curve S2 and the meridional image curve T2 of the MTF at a spatial frequency of 7 lp / mm, and the sagittal image curve S3 and the meridional image curve T3 of the MTF at a spatial frequency of 14 lp / mm are listed in

[0136] It should be further noted that the MTF of this optical system is 0.25 at a cutoff frequency of 14 lp / mm at a maximum field of view of 117°, 0.49 at a cutoff frequency of 14 lp / mm at a field of view of 93.6° at 0.8°, and 0.5 at a cutoff frequency of 14 lp / mm at a half field of view of 58.5°.

[0137] Furthermore, experimental verification showed that at a spatial frequency of 14 lp / mm, with a defocus range of ±0.05 mm, the defocus MTF of this optical system within a half-field of view of 58.5° was greater than 0.4, indicating that the optical system is not sensitive to back focus and has excellent imaging stability. The maximum meridional field curvature within the half-field of view of 58.5° was 2.083 mm, the maximum sagittal field curvature was 0.2897 mm, and the maximum optical distortion at the maximum field of view was -52%.

[0138] Figure 4 The diagram shows the relative illumination curve of the optical system operating in the far-infrared band according to Embodiment 1 of this application. See also... Figure 4 As can be seen, the relative illuminance of the optical system in this embodiment is always greater than 60% across the entire field of view; and the relative illuminance curve transitions smoothly from zero field of view to the maximum field of view without any abrupt changes. This indicates that the relative illuminance of the optical system changes uniformly from the center to the edge, meeting the requirements for relative illuminance in the excellent imaging quality standard.

[0139] Figure 5 A dot diagram of the optical system operating in the far-infrared band according to Embodiment 1 of this application is shown. See also Figure 5 As can be seen, the maximum RMS radius of the imaging point array of the optical system in this embodiment is about 2 pixels (70μm), the 0 field of view is about 1 pixel (35μm), and the half field of view within 58.5° is all within 2 pixels, which indicates that the imaging spot of the optical system is small.

[0140] Figure 6 The axial aberration curves of the optical system operating in the far-infrared band in Embodiment 1 of this application are shown. See also Figure 6 Following the order of their intersections with the horizontal axis from left to right, the three curves in the graph correspond to wavelengths of 8μm, 10μm, and 12μm, respectively. Figure 6 As can be seen, the optical system in this embodiment has a maximum axial aberration of 0.3667 mm.

[0141] Figure 7 The vertical chromatic aberration curve of the optical system operating in the far-infrared band in Embodiment 1 of this application is shown. See also Figure 6 In this embodiment, the optical system has a maximum transverse chromatic difference of 29.045 μm, which is less than one pixel.

[0142] Figure 8 A phase distribution diagram of the superlens in Embodiment 1 is shown. The horizontal axis of the phase distribution diagram represents the distance from the center of the superlens to a certain position of the superlens; the vertical axis of the phase distribution diagram represents the phase provided by the superlens at the center wavelength in the far infrared waveband at a certain position of the superlens. Referring to FIG. 6, the phase provided by the superlens at the center wavelength in the far infrared waveband at the center of the superlens is 0; the phase provided by the superlens at the center wavelength in the far infrared waveband at the edge of the superlens is 2.1π. The maximum phase difference of the superlens in the present embodiment from the center of the superlens to the edge of the superlens is 2.1π. Figure 8 The optical system in the present embodiment has a maximum phase difference of 2.1π from the center of the superlens to the edge of the superlens.

[0143] Example 2

[0144] Figure 9 A schematic diagram of the architecture layout of the optical system and the optical lens operating in the far infrared waveband in Embodiment 2 is shown. Referring to FIG. 7, the optical lens in Embodiment 2 includes, in order from the object side to the image side along the optical axis, an optical system, a window glass, and an imaging detector; the optical system includes, in order from the object side to the image side along the optical axis, a diaphragm, a superlens, and a spherical lens; the diaphragm is arranged on the object side of the superlens. Figure 9 In Embodiment 2, the optical lens includes, in order from the object side to the image side along the optical axis, an optical system, a window glass, and an imaging detector; the optical system includes, in order from the object side to the image side along the optical axis, a diaphragm, a superlens, and a spherical lens; the diaphragm is arranged on the object side of the superlens.

[0145] Table 4. System parameters of the optical system in Embodiment 2

[0146]

[0147]

[0148] As can be seen from Table 4, the F number (i.e., f / D) of the optical system in the present embodiment is 0.92, which can greatly improve the light intake of the optical system, thereby ensuring good imaging quality; at the same time, the field of view reaches 118° or above, fully satisfying the requirement of the optical system for a large field of view; at the same time, the total optical length is only 4.4 mm, fully satisfying the requirement of the optical system for miniaturization and thinness; at the same time, the relative luminance of the full field of view is greater than 65%, basically satisfying the requirement of the optical system for imaging brightness.

[0149] According to the direction from the object side to the image side, each surface in the optical system is numbered, and the parameters of each surface are summarized to obtain Table 5.

[0150] Table 5. Parameters of each surface of the optical system in Embodiment 2

[0151] Surface serial number Surface type Curvature radius (mm) Thickness (mm) Material 1 Object plane Infinite Infinite - 2 (diaphragm) Spherical surface Infinite 0.3 Si 3 Super surface Infinite 0.478 - 4 Spherical surface -4.081 1.31 Si 5 Spherical surface -2.814 1.576 - 6 Spherical surface Infinite 0.425 Si 7 Spherical surface Infinite 0.31 - 8 Image plane Infinite - -

[0152] Similarly, the explanation of Table 3 is not repeated here.

[0153] Figure 10The MTF field-of-view curve of the optical system operating in the far-infrared band according to Embodiment 2 of this application is shown. Here, X-field of view represents the field of view in the X-axis direction. Similarly, the description of the MTF field-of-view curve in Embodiment 1 will not be repeated here.

[0154] It should be noted that the MTF of the optical system in this embodiment is 0.20 at the cutoff frequency of 14 lp / mm at a maximum field of view of 118°, 0.48 at the cutoff frequency of 14 lp / mm at a field of view of 94.4° at 0.8°, and 0.61 at the cutoff frequency of 14 lp / mm at a half field of view of 59°.

[0155] Figure 11 A phase distribution diagram of the superlens in Embodiment 2 of this application is shown. The horizontal axis of the phase distribution diagram represents the distance from a certain position of the superlens to the center of the superlens; the vertical axis of the phase distribution diagram represents the phase provided by a certain position of the superlens at the center wavelength in the far-infrared band. See also Figure 11 In this embodiment, the optical system provides a phase at the center wavelength of the far-infrared band through its superlens, with a maximum phase difference of 2.6 cycles from the center of the superlens to its edge.

[0156] Example 3

[0157] Figure 12 This diagram illustrates the architectural layout of the optical system and optical lens operating in the far-infrared band according to Embodiment 3 of this application. See also... Figure 12 In embodiment 3, the optical lens includes, in sequence along the optical axis from the object side to the image side: an optical system, a window glass, and an imaging detector; wherein, the optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop, a superlens, and a spherical lens; the aperture stop is located on the object side of the superlens.

[0158] Table 6. System parameters of the optical system provided in Example 3

[0159] System parameters Optical system provided by Example 3 Effective focal length f of optical system (unit: mm) 1.4 Entrance pupil diameter D of optical system (unit: mm) 1.558 f / D 0.9 Field of view FOV (unit: °) ≥117 Optical total length TTL (unit: mm) 5 Relative illumination >61％

[0160] As shown in Table 6, the optical system in this embodiment has an F-number (i.e., f / D) of only 0.9, which can significantly increase the amount of light entering the optical system, thereby ensuring excellent imaging quality. At the same time, the field of view reaches 117° and above, which fully meets the requirements of the optical system for a large field of view. The total optical length is only 5mm, which basically meets the requirements of the optical system for miniaturization and thinness. Meanwhile, the relative illumination of the entire field of view is greater than 61%, which basically meets the requirements of the optical system for imaging brightness.

[0161] The surfaces in the optical system are numbered in the direction from the object side to the image side, and the parameters of the surfaces are summarized to obtain Table 5 below.

[0162] Table 7. Parameters of the surfaces of the optical system provided in Example 3

[0163] Surface serial number Surface type Curvature radius (mm) Thickness (mm) Material 1 Object plane Infinite Infinite - 2 (diaphragm) Spherical surface Infinite 0.3 Si 3 Super surface Infinite 0.252 - 4 Spherical surface -3.91 1.97 Si 5 Spherical surface -3.17 1.75 - 6 Spherical surface Infinite 0.425 Si 7 Spherical surface Infinite 0.31 - 8 Image plane Infinite - -

[0164] The explanation of Table 7 is omitted here for the same reason as the explanation of Table 3.

[0165] Figure 13 The MTF field curve diagram of the optical system operating in the far-infrared waveband in Example 3 provided by the present application is shown. The description of the MTF field curve diagram in Example 1 is omitted here for the same reason as the description of the MTF field curve diagram in Example 1.

[0166] It should be noted that the MTF of the optical system in this embodiment is 0.22 at the cutoff frequency of 14 lp / mm at the maximum field of view of 117°, 0.46 at the cutoff frequency of 14 lp / mm at the field of view of 0.8 of 93.6°, and 0.51 at the cutoff frequency of 14 lp / mm at the half field of view of 58.5°.

[0167] Figure 14 The phase distribution diagram of the superlens in Example 3 provided by the present application is shown. The abscissa of the phase distribution diagram represents the distance from a position of the superlens to the center of the superlens, and the ordinate of the phase distribution diagram represents the phase provided by the superlens at the center wavelength in the far-infrared waveband. Referring to Figure 14 In the optical system in this embodiment, the maximum phase difference of the phase provided by the superlens at the center wavelength in the far-infrared waveband is 2.75 periods from the center of the superlens to the edge of the superlens.

[0168] Example 4

[0169] Figure 15 The architectural layout schematic diagram of the optical system and the optical lens operating in the far-infrared waveband in Example 4 provided by the present application is shown. Referring to Figure 15 In Example 4, the optical lens comprises, in order from the object side to the image side along the optical axis: an optical system, a window glass, and an imaging detector; wherein the optical system comprises, in order from the object side to the image side along the optical axis: a diaphragm, a superlens, and a spherical lens; and the diaphragm is arranged on the object side of the superlens.

[0170] Table 8. System parameters of the optical system provided in Example 4

[0171] System parameters Optical system provided by Example 4 Effective focal length f of optical system (unit: mm) 1.5 Entrance pupil diameter D of optical system (unit: mm) 1.664 f / D 0.901 Field of view FOV (unit: °) ≥102 Optical total length TTL (unit: mm) 5 Relative illumination >71％

[0172] As shown in Table 8, the optical system in this embodiment has an F-number (i.e., f / D) of 0.901, which can significantly improve the light intake of the optical system, thereby ensuring good imaging quality. At the same time, the field of view reaches 102° or more, which basically meets the requirements of the optical system for a large field of view. Meanwhile, the total optical length is 5mm, which basically meets the requirements of the optical system for miniaturization and thinness. In addition, the relative illumination of the entire field of view is greater than 71%, which fully meets the requirements of the optical system for imaging brightness.

[0173] The surfaces in the optical system are numbered according to the direction from the object side to the image side, and the parameters of each surface are summarized to obtain Table 5 below.

[0174] Table 9. Parameters of each surface of the optical system provided in Example 4

[0175]

[0176]

[0177] Similarly, as explained in Table 3, Table 9 will not be repeated here.

[0178] Figure 16 The MTF field-of-view curve of the optical system operating in the far-infrared band in Embodiment 4 of this application is shown. Similarly, the description of the MTF field-of-view curve in Embodiment 1 will not be repeated here.

[0179] It should be noted that the MTF of the optical system in this embodiment is 0.1 at the cutoff frequency of 14 lp / mm at a maximum field of view of 102°, 0.51 at the cutoff frequency of 14 lp / mm at a field of view of 81.6° at 0.8, and 0.63 at the cutoff frequency of 14 lp / mm at a half field of view of 51°.

[0180] Figure 17 A phase distribution diagram of the superlens in Embodiment 4 of this application is shown. The horizontal axis of the phase distribution diagram represents the distance from a certain position of the superlens to the center of the superlens; the vertical axis of the phase distribution diagram represents the phase provided by a certain position of the superlens at the center wavelength in the far-infrared band. See also Figure 17 In this embodiment, the optical system provides a phase at the center wavelength of the far-infrared band through its superlens, with a maximum phase difference of 2.55 cycles from the center of the superlens to its edge.

[0181] Example 5

[0182] Figure 18The schematic diagram of the architecture layout of the optical system and the optical lens working in the far-infrared wave band in the embodiment 5 provided in the present application is shown. Referring to Figure 18 In the embodiment 5, the optical lens comprises, in sequence from the object side to the image side along the optical axis, an optical system, a window glass, and an imaging detector; wherein the optical system comprises, in sequence from the object side to the image side along the optical axis, a diaphragm, a superlens, and a spherical lens; the diaphragm is arranged on the object side of the superlens.

[0183] Table 10. System parameters of the optical system provided in the embodiment 5

[0184] System parameters Optical system provided by Example 5 Effective focal length f of optical system (unit: mm) 1.61 Entrance pupil diameter D of optical system (unit: mm) 1.8 f / D 0.89 Field of view FOV (unit: °) ≥118.5 Optical total length TTL (unit: mm) 5 Relative illumination >88％

[0185] As shown in Table 10, the F number (i.e. f / D) of the optical system in the present embodiment is only 0.89, which can greatly improve the light intake of the optical system, thereby ensuring excellent imaging quality; at the same time, the field of view angle reaches 118.5° or above, fully meeting the requirements of the optical system for a large field of view angle; at the same time, the total optical length is 5 mm, basically meeting the requirements of the optical system for miniaturization and thinness; at the same time, the relative luminance of the full field of view is greater than 88%, fully meeting the requirements of the optical system for imaging brightness.

[0186] According to the direction from the object side to the image side, each surface in the optical system is numbered, and the parameters of each surface are summarized to obtain Table 5 below.

[0187] Table 11. Parameters of each surface of the optical system provided in the embodiment 5

[0188] Surface serial number Surface type Curvature radius (mm) Thickness (mm) Material 1 Object plane Infinite Infinite - 2 (diaphragm) Spherical surface Infinite 0.3 Si 3 Super surface Infinite 0.410 - 4 Spherical surface -7.148 2.035 Si 5 Spherical surface -3.585 1.521 - 6 Spherical surface Infinite 0.425 Si 7 Spherical surface Infinite 0.31 - 8 Image plane Infinite - -

[0189] Similarly to the explanation of Table 3, Table 11 will not be described here.

[0190] Figure 19 The MTF field curve diagram of the optical system working in the far-infrared wave band in the embodiment 5 provided in the present application is shown. Similarly to the description of the MTF field curve diagram in the embodiment 1, the MTF field curve diagram in the present embodiment will not be described here.

[0191] It should be noted that the MTF of the optical system in the present embodiment is 0.26 at the cutoff frequency of 14 lp / mm at the maximum field of view of 118.5°, 0.55 at the cutoff frequency of 14 lp / mm at the field of view of 0.8 of 94.8°, and 0.49 at the cutoff frequency of 14 lp / mm at the half field of view of 59.3°.

[0192] Figure 20 The relative luminance curve diagram of the optical system working in the far-infrared wave band in the embodiment 5 provided in the present application is shown. Referring to Figure 20As can be seen, the relative illuminance of the optical system in this embodiment is always greater than 88% across the entire field of view.

[0193] Figure 21 A phase distribution diagram of the superlens in Embodiment 5 of this application is shown. The horizontal axis of the phase distribution diagram represents the distance from a certain position of the superlens to the center of the superlens; the vertical axis of the phase distribution diagram represents the phase provided by a certain position of the superlens at the center wavelength in the far-infrared band. See also Figure 21 In this embodiment, the optical system provides a phase at the center wavelength of the far-infrared band through its superlens, with a maximum phase difference of 2.45 cycles from the center of the superlens to its edge.

[0194] Example 6

[0195] Figure 22 This diagram illustrates the architectural layout of the optical system and optical lens operating in the far-infrared band according to Embodiment 6 of this application. See also... Figure 22 In embodiment 6, the optical lens includes, in sequence along the optical axis from the object side to the image side: an optical system, a window glass, and an imaging detector; wherein, the optical system includes, in sequence along the optical axis from the object side to the image side: an aperture stop, a superlens, and a spherical lens; the aperture stop is located on the object side of the superlens.

[0196] Table 12. System parameters of the optical system provided in Example 6

[0197] System parameters Optical system provided by Example 6 Effective focal length f of optical system (unit: mm) 1.61 Entrance pupil diameter D of optical system (unit: mm) 1.8 f / D 0.89 Field of view FOV (unit: °) ≥118.5 Optical total length TTL (unit: mm) 5 Relative illumination >92％

[0198] As shown in Table 12, the optical system in this embodiment has an F-number (i.e., f / D) of only 0.89, which can significantly improve the light intake of the optical system and thus ensure excellent imaging quality. At the same time, the field of view reaches 118.5° and above, which fully meets the requirements of the optical system for a large field of view. The total optical length is 5mm, which basically meets the requirements of the optical system for miniaturization and thinness. Meanwhile, the relative illumination of the entire field of view is greater than 92%, which fully meets the requirements of the optical system for imaging brightness.

[0199] The surfaces in the optical system are numbered according to the direction from the object side to the image side, and the parameters of each surface are summarized to obtain Table 5 below.

[0200] Table 13. Parameters of each surface of the optical system provided in Example 6

[0201] Surface serial number Surface type Curvature radius (mm) Thickness (mm) Material 1 Object plane Infinite Infinite - 2 (diaphragm) Spherical surface Infinite 0.3 Si 3 Super surface Infinite 0.426 - 4 Spherical surface -8.486 2.023 Si 5 Spherical surface -3.697 1.516 - 6 Spherical surface Infinite 0.425 Si 7 Spherical surface Infinite 0.31 - 8 Image plane Infinite - -

[0202] Similarly, as explained in Table 3, Table 13 will not be repeated here.

[0203] FIG. 23FIG. 7 shows a MTF field curve of the optical system in Example 6 working in the far-infrared waveband. As described for the MTF field curve in Example 1, the MTF field curve in this example will not be described again.

[0204] It should be noted that the MTF of the optical system in this example is 0.19 at the cut-off frequency of 14 lp / mm at the maximum field of view 118.5°, 0.57 at the cut-off frequency of 14 lp / mm at the 0.8 field of view 94.8°, and 0.62 at the cut-off frequency of 14 lp / mm at the half field of view 59.3°.

[0205] FIG. 24 FIG. 8 shows a relative illumination curve of the optical system in Example 6 working in the far-infrared waveband. Referring to FIG. 8, the horizontal axis represents the field of view, and the vertical axis represents the relative illumination. FIG. 24 It can be seen that the relative illumination of the optical system in this example is always greater than 92% in the full field of view range.

[0206] FIG. 25 FIG. 9 shows a phase distribution diagram of the superlens in Example 6. The horizontal axis of the phase distribution diagram represents the distance from a position of the superlens to the center of the superlens, and the vertical axis of the phase distribution diagram represents the phase provided by the position of the superlens at the center wavelength in the far-infrared waveband. Referring to FIG. 9, FIG. 25 In this example, the maximum phase difference of the phase provided by the superlens of the optical system at the center wavelength in the far-infrared waveband is 1.7 periods from the center of the superlens to the edge of the superlens.

[0207] Example 7

[0208] FIG. 26 FIG. 10 shows a schematic layout diagram of the optical system and the optical lens in Example 7 working in the far-infrared waveband. Referring to FIG. 10, FIG. 26 In Example 7, the optical lens includes, along the optical axis from the object side to the image side, in order: the optical system, the window glass, and the imaging detector; wherein the optical system includes, along the optical axis from the object side to the image side, in order: the superlens, the diaphragm, and the spherical lens; and the diaphragm is arranged on the image side of the superlens.

[0209] Table 14. System parameters of the optical system provided in Example 7

[0210] System parameters Optical system provided in Example 7 Effective focal length f of the optical system (unit: mm) 1.54 Entrance pupil diameter D of the optical system (unit: mm) 1.8 f / D 0.86 Field of view FOV (unit: °) ≥118.9 Total track length TTL of the optical system (unit: mm) 5 Relative luminance >93％

[0211] As shown in Table 14, the F number (i.e., f / D) of the optical system in this embodiment is only 0.86, which can greatly improve the light amount of the optical system, thereby ensuring excellent imaging quality; at the same time, the field of view angle reaches 118.9° and above, fully meeting the requirements of the optical system for a large field of view angle; at the same time, the total optical length is 5 mm, which basically meets the requirements of the optical system for miniaturization and thinness; at the same time, the relative luminance of the full field of view is greater than 93%, fully meeting the requirements of the optical system for imaging brightness.

[0212] According to the direction from the object side to the image side, each surface in the optical system is numbered, and the parameters of each surface are summarized to obtain the following Table 5.

[0213] Table 15. Parameters of each surface of the optical system provided in Embodiment 7

[0214]

[0215]

[0216] Similarly, the explanation of Table 3 is not repeated here.

[0217] FIG. 27 The MTF field curve diagram of the optical system working in the far-infrared waveband in Embodiment 7 provided by the present application is shown. Similarly, the description of the MTF field curve diagram in Embodiment 1 is not repeated here.

[0218] It should be noted that the MTF of the optical system in this embodiment is 0.22 at the cutoff frequency of 14 lp / mm at the maximum field of view of 118.9°, 0.47 at the cutoff frequency of 14 lp / mm at the 0.8 field of view of 95.1°, and 0.43 at the cutoff frequency of 14 lp / mm at the half field of view of 59.5°.

[0219] FIG. 28 The relative luminance curve diagram of the optical system working in the far-infrared waveband in Embodiment 7 provided by the present application is shown. Referring to FIG. 28 It can be seen that the relative luminance of the optical system in this embodiment is always greater than 93% in the full field of view range.

[0220] FIG. 29 The phase distribution diagram of the superlens in Embodiment 7 provided by the present application is shown. The horizontal axis of the phase distribution diagram represents the distance from a position of the superlens to the center of the superlens; the vertical axis of the phase distribution diagram represents the phase provided by a position of the superlens at the center wavelength in the far-infrared waveband. Referring to FIG. 29The optical system in the embodiment provides a phase of 2.1 periods at the center wavelength in the far-infrared waveband.

[0221] The lens parameters of the optical systems provided in the above seven embodiments are summarized in Table 16 as shown below. Table 16 is mainly used to illustrate that the conditions met by the optical systems provided in the present application are verified and supported by experiments.

[0222] Table 16. Lens parameters of the optical systems provided in the embodiments

[0223]

[0224]

[0225] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An optical system operating in the far infrared waveband, characterised in that, The optical system comprises, along the optical axis from the object side to the image side, in sequence: a superlens, a spherical lens; the number of lenses with optical power in the optical system is two; the superlens is used to correct high-order residual aberrations; the spherical lens is used to correct low-order primary aberrations; the superlens and the spherical lens are used together to correct chromatic aberration of the optical system; the absolute value of the curvature radius of the object side surface of the spherical lens is greater than the absolute value of the curvature radius of the image side surface of the spherical lens; The optical system satisfies the following conditions: 0.83≤f / D≤0.92 Wherein, f is the effective focal length of the optical system, and D is the entrance pupil diameter of the optical system.

2. The optical system of claim 1, wherein The optical system also satisfies the following conditions: wherein f M is the effective focal length of the superlens, is the maximum phase difference of the phase provided by the superlens at a single wavelength, R M is the optically effective radius of the superlens.

3. The optical system of claim 1, wherein The optical system also satisfies the following conditions: 1.0＜r1 / r2＜2.8 Wherein, r1 is the curvature radius of the object side surface of the spherical lens, and r2 is the curvature radius of the image side surface of the spherical lens.

4. The optical system of claim 1, wherein The optical system also satisfies the following conditions: 0.40 < R M / R G ≤ 0.55 wherein R M is the optical effective radius of the superlens, and R G is the optical effective radius of the spherical lens.

5. The optical system of claim 1, wherein The optical system also satisfies the following conditions: 1 < f M f < 1.85 where f M is the effective focal length of the hyperlens.

6. The optical system of claim 1, wherein The optical system also satisfies the following conditions: 1.25 < f G f < 1.75 wherein f G is the effective focal length of the spherical lens.

7. The optical system of claim 1, wherein The optical system also satisfies the following conditions: 3.3≤n M ≤4.3 3.3≤n G ≤4.3 wherein n M is the refractive index of the superlens, n G is the refractive index of the spherical lens.

8. The optical system of claim 1, wherein, The optical system is also provided with a diaphragm; the diaphragm is arranged on the surface of the superlens, or the diaphragm is arranged in space with the superlens.

9. The optical system of claim 1, wherein, The super surface of the superlens is arranged on the image side surface of the superlens.

10. An optical lens operating in the far infrared waveband, characterised in that, The optical lens comprises the optical system according to any one of claims 1-9, and an imaging detector arranged on the image surface.

Images