Infrared optical system and infrared optical lens

Abstract

The utility model discloses an infrared optical system and an infrared optical lens. The infrared optical system sequentially comprises a first aspheric lens, a super lens and a second aspheric lens from an object side to an image side, the first aspheric lens is a positive lens, the surface, close to the image side, of the first aspheric lens protrudes towards the object side, the surface, away from the image side, of the first aspheric lens protrudes towards the object side, and the super lens is a positive lens; the surface, close to the object side and the surface, away from the object side, of the second aspheric lens protrude towards the image side or the object side. According to the infrared optical system provided by the invention, the number of used lenses is relatively small while the imaging quality requirement is met, and the production cost of the infrared optical system can be reduced. And meanwhile, the total optical length of the infrared optical system is relatively short, so that the light weight and miniaturization of the infrared optical system are realized.

Description

Technical Field

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

[0002] The lens is generally composed of two parts: the optical system and the structural parts. Infrared lens, also known as infrared thermal imaging lens, generally refers to an imaging lens with a working wavelength of 8-14μm. Infrared lens can make up for the defects of visible light imaging lens, and can replace visible light imaging in fog, haze, rain, snow, night and other environments. It is widely used in security, automotive, military and other fields.

[0003] When the temperature changes, the optical elements of the infrared lens usually undergo thermal expansion, thereby affecting the imaging quality of the infrared lens. In the prior art, the infrared lens usually includes multiple meniscus lenses, and some of the meniscus lenses are positive lenses, and the other meniscus lenses are negative lenses. The positive and negative lenses move in opposite directions when the temperature changes to reduce the thermal difference. However, the provision of multiple lenses usually increases the production cost of the lens and usually results in a relatively large volume of the lens. Utility Model Content

[0004] In view of the above technical problems, the embodiments of the present application provide an infrared optical system and an infrared optical lens, which aim to solve the problem of relatively large volume of infrared optical lenses in the prior art.

[0005] According to one aspect of an embodiment of the present application, an infrared optical system is disclosed, wherein the infrared optical system includes, in order from the object side to the image side along the optical axis: a first aspheric lens, a super lens, and a second aspheric lens; the first aspheric lens is a positive lens, the surface of the first aspheric lens close to the image side is convex toward the object side, and the surface of the first aspheric lens away from the image side is convex toward the object side; the super lens is a positive lens; the second aspheric lens has an inflection point, and the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex toward the image side or the object side;

[0006] Wherein, when the surface of the second aspheric lens close to the object side and the surface far from the object side are both convex toward the object side, the second aspheric lens is a negative lens.

[0007] In some embodiments, the infrared optical system satisfies the following condition: Wherein, f is the effective focal length of the infrared optical system, t is the temperature; n a1 is the refractive index of the first aspheric lens, the f a1 is the focal length of the first aspheric lens; a2 is the refractive index of the second aspheric lens, the fa2 is the focal length of the second aspheric lens.

[0008] In some embodiments, the infrared optical system satisfies the following condition: Wherein, f is the effective focal length of the infrared optical system, and TTL is the total optical length of the infrared optical system.

[0009] In some embodiments, the infrared optical system satisfies the following condition: Wherein, the BFL is the optical back focus of the infrared optical system, and the TTL is the total optical length of the infrared optical system.

[0010] In some embodiments, the infrared optical system satisfies the following condition: Among them, the f m1 is the focal length of the superlens, and f is the effective focal length of the infrared optical system.

[0011] In some embodiments, the infrared optical system satisfies the following condition: Among them, the f a1 is the focal length of the first aspheric lens, and the f a2 is the focal length of the second aspheric lens.

[0012] In some embodiments, the infrared optical system satisfies the following condition: Wherein, f is the effective focal length of the infrared optical system, and D is the entrance pupil diameter of the infrared optical system.

[0013] In some embodiments, the infrared optical system further includes a stop, and the stop is disposed on a surface of the first aspheric lens, or the stop is spaced apart from the first aspheric lens.

[0014] In some embodiments, when the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex toward the image side, the second aspheric lens is a positive lens, and the surface of the second aspheric lens away from the object side has at least one inflection point.

[0015] In some embodiments, when the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex toward the image side, the second aspheric lens is a negative lens, and the surface of the second aspheric lens away from the object side has at least one inflection point.

[0016] In some embodiments, when the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex toward the object side, the surface of the second aspheric lens close to the object side has at least one inflection point.

[0017] A second aspect of an embodiment of the present application provides an infrared optical lens, comprising an imaging detector and the above-mentioned infrared optical system; the imaging detector is arranged on the image plane of the infrared optical system.

[0018] The infrared optical system provided by the present application includes, from the object side to the image side, a first aspheric lens, a super lens, and a second aspheric lens; the first aspheric lens is a positive lens, the surface of the first aspheric lens close to the image side is convex to the object side, the surface of the first aspheric lens away from the image side is convex to the object side, the super lens is a positive lens, and the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex to the image side or the object side. The infrared optical system provided by the present application uses a relatively small number of lenses while meeting the imaging quality requirements, and avoids the use of germanium lenses, which can reduce the production cost of the infrared optical system. At the same time, the total optical length of the infrared optical system is relatively short, which realizes the lightweight and miniaturization of the infrared optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0020] Figure 1 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown.

[0021] Figure 2 The MTF field of view curve of the infrared optical system at 20° C. in one embodiment of the present application is shown.

[0022] Figure 3 The MTF field of view curve of the infrared optical system at -40°C in one embodiment of the present application is shown.

[0023] Figure 4 The MTF field of view curve of the infrared optical system at 80° C. in one embodiment of the present application is shown.

[0024] Figure 5 A field curvature diagram of an infrared optical system in an embodiment of the present application is shown.

[0025] Figure 6 A distortion diagram of an infrared optical system in an embodiment of the present application is shown.

[0026] Figure 7 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown.

[0027] Figure 8 The MTF field of view curve of the infrared optical system at 20° C. in one embodiment of the present application is shown.

[0028] Fig. 9The MTF field of view curve of the infrared optical system at -40°C in one embodiment of the present application is shown.

[0029] Fig.10 The MTF field of view curve of the infrared optical system at 80° C. in one embodiment of the present application is shown.

[0030] Fig.11 A field curvature diagram of an infrared optical system in an embodiment of the present application is shown.

[0031] Fig.12 A distortion diagram of an infrared optical system in an embodiment of the present application is shown.

[0032] Fig.13 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown.

[0033] Fig.14 The MTF field of view curve of the infrared optical system at 20° C. in one embodiment of the present application is shown.

[0034] Fig.15 The MTF field of view curve of the infrared optical system at -40°C in one embodiment of the present application is shown.

[0035] Fig.16 The MTF field of view curve of the infrared optical system at 80° C. in one embodiment of the present application is shown.

[0036] Fig.17 A field curvature diagram of an infrared optical system in an embodiment of the present application is shown.

[0037] Fig.18 A distortion diagram of an infrared optical system in an embodiment of the present application is shown.

[0038] Fig.19 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown.

[0039] Fig. 20 The MTF field of view curve of the infrared optical system at 20° C. in one embodiment of the present application is shown.

[0040] Fig.21 The MTF field of view curve of the infrared optical system at -40°C in one embodiment of the present application is shown.

[0041] Fig. 22 The MTF field of view curve of the infrared optical system at 80° C. in one embodiment of the present application is shown.

[0042] Fig.23 A field curvature diagram of an infrared optical system in an embodiment of the present application is shown.

[0043] Fig.24A distortion diagram of an infrared optical system in an embodiment of the present application is shown.

[0044] Figure numerals: 100, infrared optical system; 1, first aspheric lens; 2, super lens; 3, second aspheric lens; 4, aperture; 5, protective member; 6, window material; A, object side; B, image side; S, optical axis. DETAILED DESCRIPTION

[0045] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0046] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other modules, components, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application unclear.

[0047] The present application provides an infrared optical system. The prior art that is closest to the specifications to be achieved by the present application is Chinese patent CN218675476U. Chinese patent CN218675476U discloses an athermal lens for use in large-target infrared detectors. The effective focal length of the lens is close to that of the infrared optical system provided by the present application, but the total optical length of the lens reaches 56 mm, which is not conducive to the miniaturization of the lens.

[0048] See also Figure 1 , Figure 7 , Fig.13 and Fig.19 , Figure 1 , Figure 7 , Fig.13 and Fig.19 Schematic diagrams of the architectural layout of the infrared optical system 100 in different embodiments of the present application are respectively shown. In the infrared optical system 100, the object side A is located on one side of the infrared optical system 100, the image side B is located on the other side of the infrared optical system 100, and the optical axis S is the center line of the light beam passing through the infrared optical system 100.

[0049] The infrared optical system 100 includes a first aspheric lens 1, a super lens 2 and a second aspheric lens 3. The first aspheric lens 1, the super lens 2 and the second aspheric lens 3 are arranged in sequence along the optical axis S from the object side A to the image side B.

[0050] The first aspheric lens 1 is a positive lens used to provide optical power. The surface of the first aspheric lens 1 close to the object side A is convex toward the object side A, and the surface of the first aspheric lens 1 away from the object side A is convex toward the object side A.

[0051] The super lens 2 is a positive lens, which is used to converge light and correct aberrations. The super lens 2 provides different focal lengths at different wavelengths. The super lens 2 combined with the first aspheric lens 1 and the second aspheric lens 3 can correct the chromatic aberration of the infrared optical system 100.

[0052] The super lens 2 includes a substrate and a super structure unit located on the surface of the substrate. The vertices and / or centers of the super structure units are provided with micro-nano structures. The filling material between the micro-nano structures is air or other materials that are transparent in the working band. The micro-nano structures are arranged on the surface of the super lens 2 close to the object side A and / or the surface close to the image side B. It should be noted that although Figure 1 , Figure 7 , Fig.13 and Fig.19 The micro-nano structure is arranged on the surface of the superlens 2 close to the object side A, but the micro-nano structure is arranged on the surface of the superlens 2 close to the image side B also within the protection scope of the present application.

[0053] The phase distribution of superlens 2 satisfies the following formula:

[0054]

[0055]

[0056] Wherein, r is the distance from the center of the superlens 2 to any nanostructure; λ is the operating wavelength of the superlens 2; is any phase related to the working wavelength of the superlens 2; (x, y) is the mirror coordinate of the superlens; a i and b i are real coefficients.

[0057] The surface of the second aspheric lens 3 close to the object side A and the surface away from the object side A are both convex toward the image side B or the object side A. The second aspheric lens 3 is a negative lens or a positive lens with very small optical power. When the second aspheric lens 3 is a positive lens, it is mainly used to correct aberrations.

[0058] See also Figure 1 and Fig.19In some embodiments, the second aspheric lens 3 is a positive lens, the surface of the second aspheric lens 3 close to the object side A is convex toward the image side B, the surface of the second aspheric lens 3 away from the object side A is convex toward the image side B, and the surface of the second aspheric lens 3 away from the object side A has at least one inflection point.

[0059] See also Figure 7 In some embodiments, the second aspheric lens 3 is a negative lens, the surface of the second aspheric lens 3 close to the object side A is convex toward the image side B, the surface of the second aspheric lens 3 away from the object side A is convex toward the image side B, and the surface of the second aspheric lens 3 away from the object side A has at least one inflection point.

[0060] See also Fig.13 In some embodiments, the second aspheric lens 3 is a negative lens, the surface of the second aspheric lens 3 close to the object side A is convex toward the object side A, the surface of the second aspheric lens 3 close to the object side A has at least one inflection point; the surface of the second aspheric lens 3 away from the object side A is convex toward the object side A.

[0061] In the present application, the infrared optical system 100 is composed of a metalens 2 and two conventional lenses. The infrared optical system 100 uses a relatively small number of lenses while meeting the imaging quality requirements, and avoids the use of germanium lenses, which can reduce the production cost of the infrared optical system 100. At the same time, the total optical length of the infrared optical system 100 is relatively short, achieving lightweight and miniaturization of the infrared optical system 100.

[0062] In some embodiments, the infrared optical system 100 satisfies the following conditional formula:

[0063]

[0064] Wherein, f is the effective focal length of the infrared optical system 100, and its unit is the unit of length. t is the temperature, and dt is the change in temperature. a1 is the refractive index of the first aspheric lens 1, dn a1 is the change in the refractive index of the first aspherical lens 1. a1 is the focal length of the first aspheric lens 1, and its unit is a length unit, is the coefficient of variation of the refractive index of the first aspherical lens 1 with temperature. a2 is the refractive index of the second aspherical lens 3, dn a2 is the change in the refractive index of the second aspherical lens 3. a2 is the focal length of the second aspherical lens 3, and its unit is a length unit, is the coefficient of variation of the refractive index of the second aspheric lens 3 with temperature. The effective focal length f of the infrared optical system 100 and the focal length f of the first aspheric lens 1 are a1 and the focal length f of the second aspherical lens 3a2 have the same dimension, for example, millimeters.

[0065] for The lower limit is used to avoid over-compensation of temperature, and the upper limit is used to avoid excessive influence of temperature on the imaging performance of the infrared optical system 100, resulting in a decrease in imaging quality. The value of is controlled between -11 / °C and 26 / °C, which can reduce the influence of temperature changes on the optimal imaging surface position of the infrared optical system 100, thereby avoiding excessive influence of temperature changes on imaging quality.

[0066] In some embodiments, the infrared optical system 100 has a good thermal elimination effect in an environment of -40°C to 80°C, so that the infrared optical system 100 can be used in many scenarios, such as high temperature outdoors, extremely cold outdoors, and factories with a large temperature fluctuation range.

[0067] In some embodiments, the infrared optical system 100 satisfies the following conditional formula:

[0068]

[0069] Wherein, f is the effective focal length of the infrared optical system 100, and its unit is the length unit. TTL (Total Track Length, referred to as TTL) is the total optical length of the infrared optical system 100, and TTL refers to the distance from the center of the front surface of the first lens of the optical system to the image plane, and its unit is the length unit. The dimension of the total optical length is the same as the dimension of the effective focal length of the infrared optical system 100, for example, both are millimeters. In this embodiment, TTL refers to the distance from the center of the surface of the first aspheric lens 1 close to the object side A to the image plane.

[0070] for The lower limit of this value is used to limit the total optical length of the infrared optical system 100, which can avoid the total optical length being too long and enable the infrared optical system 100 to meet the requirements of lightweight and miniaturization. The upper limit can ensure that the infrared optical system 100 has a larger effective focal length f, thereby ensuring that the F number is close to the requirement.

[0071] In some embodiments, the infrared optical system 100 satisfies the following conditional formula:

[0072]

[0073] Wherein, BFL is the optical back focus of the infrared optical system 100, and its unit is a length unit. In this embodiment, the optical back focus of the infrared optical system 100 is the distance from the vertex of the surface of the second aspherical lens 3 close to the image plane on the optical axis S to the image plane. TTL is the total optical length of the infrared optical system 100, and its definition can be referred to above and will not be elaborated here. The dimension of the total optical length is the same as that of the optical back focus, for example, both are millimeters.

[0074] for The lower limit is to ensure that the optical back focus of the infrared optical system 100 has a suitable length, so as to facilitate the assembly of the lens corresponding to the infrared optical system 100. The upper limit is to minimize the total optical length of the infrared optical system 100, thereby reducing the weight of the lens corresponding to the infrared optical system 100 and realizing miniaturization of the lens.

[0075] In some embodiments, the total optical length of infrared optical system 100 is less than 44.5 mm.

[0076] In some embodiments, the infrared optical system 100 satisfies the following conditional formula:

[0077]

[0078] Among them, f m1 is the focal length of the metalens 2, and its unit is a length unit. f is the effective focal length of the infrared optical system 100, and its unit is a length unit. The dimension of the focal length of the metalens 2 is the same as that of the effective focal length of the infrared optical system, for example, both are millimeters.

[0079] for The value of represents the focal length proportion of the superlens 2 in the infrared optical system 100, reflecting the contribution of the superlens 2 in focusing. The lower limit is to avoid the focal length of the metalens 2 being too small. The smaller the focal length of the metalens 2, the greater its optical power. Since the phase gradient of the metalens 2 with a large optical power is large, it will cause a large processing error of the micro-nano structure. Therefore, The lower limit of can avoid large processing errors of the superlens 2. The upper limit is to ensure that the superlens 2 plays a role in the system and can effectively reduce aberrations.

[0080] Furthermore, in some embodiments, the infrared optical system 100 satisfies the following conditional formula:

[0081]

[0082] The value of is between 12 and 126, which can make the superlens 2 have a suitable optical focal length and prevent the processing error from being too large. At the same time, it can also make the superlens 2 play a greater role in the system and effectively reduce the aberration.

[0083] In some embodiments, the infrared optical system 100 satisfies the following conditional formula:

[0084]

[0085] Among them, f a1 is the focal length of the first aspherical lens 1, and its unit is a length unit. a2 is the focal length of the second aspheric lens 3, and its unit is a length unit. The dimension of the focal length of the first aspheric lens 1 is the same as the dimension of the focal length of the second aspheric lens 3, for example, both are millimeters.

[0086] for The lower limit of is a negative number, in which case the first aspheric lens 1 is a positive lens and the second aspheric lens 3 is a negative lens. When the temperature changes, the focus movement directions of the positive lens and the negative lens are opposite. Therefore, the combination of the two can make the movement amount of the focus of the infrared optical system 100 smaller, and can reduce the influence of the temperature on the focus of the infrared optical system 100, that is, The lower limit of the passive athermal design can be achieved by combining positive and negative lenses.

[0087] The upper limit of is a positive value, in which case the first aspheric lens 1 and the second aspheric lens 3 are both positive lenses. is less than 1, so f a1 Less than f a2 At this time, the first aspheric lens 1 mainly plays the role of providing optical power, and the second aspheric lens 3 mainly plays the role of correcting aberrations.

[0088] In some embodiments, the infrared optical system 100 satisfies the following conditional formula:

[0089]

[0090] Wherein, f is the effective focal length of the infrared optical system 100, and its unit is a length unit. D is the entrance pupil diameter of the infrared optical system 100, and its unit is a length unit. The dimension of the effective focal length of the infrared optical system 100 is the same as the dimension of the entrance pupil diameter of the infrared optical system 100, for example, both are millimeters.

[0091] The value is the F number, also called the aperture number. The smaller the F number, the larger the aperture. A large aperture can greatly increase the amount of light entering the infrared optical system 100, and collect as much energy as possible entering the infrared optical system 100 when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.

[0092] In some embodiments, the maximum field of view of the infrared optical system 100 at a frequency of 42lp / mm has an MTF (Modulation Transfer Function, MTF for short) of about 0.3. The modulation transfer function is also called the spatial contrast transfer function and the spatial frequency contrast sensitivity function. It is a function of spatial frequency and reflects the ability of the optical system to transfer the modulation degree of sinusoidal objects of various frequencies. The maximum field of view of the infrared optical system 100 at a frequency of 42lp / mm has an MTF of about 0.3, indicating that the edge image quality of the infrared optical system 100 is better.

[0093] The infrared optical system 100 further includes an aperture 4, which is used to limit the incident aperture of the light beam, thereby affecting the imaging quality and performance of the optical system.

[0094] In some embodiments, the aperture 4 is disposed on the surface of the first aspheric lens 1. Specifically, the aperture 4 is disposed on the surface of the first aspheric lens 1 close to the object side A. Alternatively, the aperture 4 is disposed on the surface of the first aspheric lens 1 close to the image side B.

[0095] In some embodiments, the aperture 4 is spaced apart from the first aspheric lens 1. Specifically, the aperture 4 is disposed on a side of the first aspheric lens 1 away from the super lens 2, and the aperture 4 is spaced apart from the first aspheric lens 1. Alternatively, the aperture 4 is disposed between the first aspheric lens 1 and the super lens 2.

[0096] In some embodiments, the distortion of the infrared optical system 100 is less than 2%. Therefore, the distortion of the infrared optical system 100 is small and the imaging quality is better.

[0097] In some embodiments, the operating wavelength band of the infrared optical system 100 is far infrared.

[0098] The present application also provides an infrared optical lens (not shown), which includes the above-mentioned infrared optical system and an imaging detector (not shown). The structure of the infrared optical system can be found above and will not be described in this article. The imaging detector is arranged on the image plane of the infrared optical system 100. In the present application, the image plane is the surface corresponding to the image side B. The imaging detector includes but is not limited to CMOS (Complementary Metal Oxide Semiconductor, referred to as CMOS, complementary metal oxide semiconductor) and CCD (Charge Coupled Device, referred to as CCD, charge coupled device).

[0099] In some embodiments, the infrared optical lens further includes a protective member 5, which is located along the optical axis S on the side of the second aspheric lens 3 away from the super lens 2. The protective member 5 can transmit light and is used to isolate the external environment, thereby reducing the probability of damage to the devices inside it.

[0100] The protective member 5 may be in the form of protective glass, but the protective member 5 is not limited to silicon glass. For example, the protective member 5 may be made of germanium glass.

[0101] In one embodiment, the infrared optical lens further includes a window material 6, which is located on the side of the protective member 5 away from the second aspherical lens 3 along the optical axis S. The window material 6 can be used to isolate the external environment, protect the internal components, and has a high transmittance to light of a specific wavelength or wavelength range. In the present application, the window material 6 has a high transmittance to infrared light and acts as a window. The window material 6 has various forms and can be single crystal, polycrystalline, glass or film.

[0102] The present application exemplarily provides four infrared optical lenses that meet usage requirements in four embodiments. Next, the infrared optical lenses provided in each embodiment of the present application are introduced in detail.

[0103] Example 1

[0104] Figure 1 The schematic diagram of the structure layout of the infrared optical lens in Example 1 is shown. Figure 1 The mid-infrared optical lens includes, in sequence from the object side A to the image side B along the optical axis S: an aperture 4, a first aspherical mirror 1, a super lens 2, a second aspherical mirror 3, a protective member 5 and a window material 6.

[0105] Table 1. Some parameters of infrared optical lens

[0106] System Parameters data Total optical length (TTL) 44.12mm Field of view (2ω) 13.44° F-number 1.18 Effective focal length 41.42mm Working band Long-wave infrared (8μm~12μm)

[0107] As can be seen from Table 1, the infrared optical lens in this embodiment has an operating band of 8 to 12 microns, which meets the working requirements of the far-infrared band. The F number (aperture) of the infrared optical lens is 1.18, which can greatly increase the amount of light entering the infrared optical lens, and collect as much energy as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality. At the same time, the total optical length of the infrared optical lens is only 44.12 mm, which fully meets the requirements of the infrared optical lens for miniaturization and thinness, and is conducive to the control of its volume.

[0108] Starting from the object plane, along the optical axis S from the object side A to the image side B, each surface in the optical system is numbered, and the parameters of each surface are summarized to obtain the following Table 2.

[0109] Table 2. Parameters of various surfaces in the infrared optical lens provided in Example 1

[0110] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 0 Physical surface unlimited 1e6 - 1 Aperture unlimited -7.72 - 2 Aspheric 23.26 5.47 Sulfur 3 Aspheric 28.93 5.41 - 4 Metasurface unlimited 0.3 silicon 5 Spherical unlimited 10.64 - 6 Aspheric -36.23 3.15 Sulfur 7 Aspheric -38.14 17.49 - 8 Spherical unlimited 0.3 germanium 9 Spherical unlimited 0.5 - 10 Spherical unlimited 0.725 silicon 11 Spherical unlimited 0.14 - 12 Image plane unlimited - -

[0111] For each surface in Table 2, surface 0 is the object surface, and surface 1 is the surface of the aperture 4 close to the object side A. Surface 2 is the surface of the first aspheric lens 1 close to the object side A, and surface 3 is the surface of the first aspheric lens 1 away from the object side A. Surface 4 is the surface of the superlens 2 close to the object side A. Since the micro-nano structure is arranged on the surface of the superlens 2 close to the object side A, it is recorded as a super surface, and surface 5 is the surface of the superlens 2 away from the object side A. Surface 6 is the surface of the second aspheric lens 3 close to the object side A, and surface 7 is the surface of the second aspheric lens 3 away from the object side A. Surface 8 is the surface of the protective member 5 close to the object side A, and surface 9 is the surface of the protective member 5 away from the object side A. Surface 10 is the surface of the window material 6 close to the object side A, and surface 11 is the surface of the window material 6 away from the object side A. Surface 12 is the image surface.

[0112] Please refer to Table 2 again. Since the focusing distance of the optical system in this embodiment is 1 km, the distance from the object plane 0 to the surface 1 is 1e6 (10 6) mm. The radius of curvature of surface 1 is infinite, so surface 1 is a plane. The distance between surface 1 and surface 2 is -7.72 mm. It should be noted that the negative sign in the distance -7.72 mm indicates that surface 1 is located behind surface 2 along the direction from object side A to image side B. The material between surface 1 and surface 2 is air. The radius of curvature of surface 2 is 23.26 mm, the distance between surface 2 and surface 3 is 5.47 mm, and the material between surface 2 and surface 3 is chalcogenide glass. The radius of curvature of surface 3 is 28.93 mm, the distance between surface 3 and surface 4 is 5.41 mm, and the material between surface 3 and surface 4 is air. The radius of curvature of surface 4 is infinite, so surface 4 is a plane. The distance between surface 4 and surface 5 is 0.3 mm, and the material between surface 4 and surface 5 is silicon. The radius of curvature of surface 5 is infinite, so surface 5 is a plane. The distance between surface 5 and surface 6 is 10.64 mm, and the material between surface 5 and surface 6 is air. The radius of curvature of surface 6 is -36.23 mm, the distance between surface 6 and surface 7 is 3.15 mm, and the material between surface 6 and surface 7 is chalcogenide glass. The radius of curvature of surface 7 is -38.14 mm, the distance between surface 7 and surface 8 is 17.49 mm, and the material between surface 7 and surface 8 is air. The radius of curvature of surface 8 is infinite, so surface 8 is a plane. The distance between surface 8 and surface 9 is 0.3 mm, and the material between surface 8 and surface 9 is germanium. The radius of curvature of surface 9 is infinite, so surface 9 is a plane. The distance between surface 9 and surface 10 is 0.5 mm, and the material between surface 9 and surface 10 is air. The radius of curvature of surface 10 is infinite, so surface 10 is a plane. The distance between surface 10 and surface 11 is 0.725 mm, and the material between surface 10 and surface 11 is silicon. The radius of curvature of surface 11 is infinite, so surface 11 is a plane. The distance between the surface 11 and the surface 12 is 0.14 mm, and the material between the surface 11 and the surface 12 is air.

[0113] Surface 2, surface 3, surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0114]

[0115] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis S direction; c is the curvature of the aspherical surface, c=1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D are the aspherical coefficients. The values ​​of k, A, B, C, D, etc. of surface 2, surface 3, surface 6 and surface 7 can be obtained from Table 3.

[0116] Table 3. Coefficients of the even-order aspheric surfaces in the infrared optical lens provided in Example 1

[0117] Surface serial number K A B C D E F G 2 -7.44E-02 4.03E-07 -8.56E-11 -5.56E-13 5.79E-15 0.00 0.00 0.00 3 6.27E-02 -1.15E-06 -3.00E-09 -5.99E-13 5.46E-15 0.00 0.00 0.00 6 7.70E+00 9.59E-05 -7.11E-07 1.20E-08 -2.11E-11 -4.36E-13 2.32E-15 2.39E-19 7 4.82E+00 8.60E-05 -3.20E-07 2.06E-09 7.02E-11 6.45E-15 -9.53E-15 5.57E-17

[0118] See also Figures 2 to 4 , Figures 2 to 4 The MTF field of view curves of the infrared optical lens provided in this application are shown at 20° C., -40° C., and 80° C. MTF is an important indicator used to describe the imaging quality of an optical system. The closer the MTF value is to the diffraction limit, the better the imaging quality.

[0119] Figure 2 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm (line pairs / mm) spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at 20℃, the MTF of the infrared optical lens within the 4.93mm field of view is always greater than 0.3, so the infrared optical lens has better image quality. Among them, Figure 3 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0120] Figure 3 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at -40℃, the MTF of the infrared optical lens within the 4.93mm field of view is always greater than 0.29, so the infrared optical lens has better image quality. Among them, Figure 4 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0121] Figure 4 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at 80℃, the MTF of the infrared optical lens within the 4.93mm field of view is always greater than 0.25, so the infrared optical lens has better image quality. Among them, Figure 4 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0122] comprehensive Figures 2 to 4 It can be seen that, taking the center of the field of view as an example, the MTF value of the sagittal curve S1 of the optical lens at 20°C at a spatial frequency of 10lp / mm is 0.84, the MTF value of the sagittal curve S1 of the optical lens at -40°C at a spatial frequency of 10lp / mm is 0.82, and the MTF value of the sagittal curve S1 of the optical lens at 80°C at a spatial frequency of 10lp / mm is 0.83. Therefore, at the same spatial frequency (10lp / mm), when the temperature changes from 20°C to -40°C or even 80°C, the MTF value of the infrared optical lens changes little. Similarly, at other spatial frequencies (42lp / mm, 21lp / mm), when the temperature changes from 20°C to -40°C or even 80°C, the MTF value of the infrared optical lens also changes little. Therefore, the imaging quality of the infrared optical lens provided in this embodiment is less affected by temperature.

[0123] Figure 5 The figure shows the field curvature of the infrared optical lens provided in this embodiment under different wavelengths of infrared light. Figure 5 The field curvatures L1, L2 and L3 of far-infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the meridional direction, and the field curvatures L4, L5 and L6 of far-infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the sagittal direction are shown respectively. Figure 5 The horizontal axis is the distance deviation between the actual focus of the light and the image plane, and its unit is millimeter. Figure 5 The vertical coordinate is the field of view along the positive direction of the Y axis, and its unit is degree.

[0124] Depend on Figure 5 It can be seen that the maximum value of the field curvature L1 of the far-infrared light with a wavelength of 8 microns in the meridional direction is 0.0034 mm, and the maximum value of the field curvature L4 of the far-infrared light with a wavelength of 8 microns in the sagittal direction is 0.0336 mm. The maximum value of the field curvature L2 of the far-infrared light with a wavelength of 10 microns in the meridional direction is 0.001 mm, and the maximum value of the field curvature L5 of the far-infrared light with a wavelength of 10 microns in the sagittal direction is 0.031 mm. The maximum value of the field curvature L3 of the far-infrared light with a wavelength of 12 microns in the meridional direction is 0.0033 mm, and the maximum value of the field curvature L6 of the far-infrared light with a wavelength of 12 microns in the sagittal direction is 0.0335 mm. Therefore, the maximum field curvature of the infrared optical lens is 0.0336 mm, and the field curvature of the infrared optical lens is small, which meets the requirements for field curvature in the excellent imaging quality standard.

[0125] Figure 6 The distortion of the infrared optical lens provided in this embodiment under 8 micron, 10 micron and 12 micron wavelength infrared light ( Figure 6 There are three curves in total, but the gaps between the three curves are very small, resulting in the three curves almost overlapping). Figure 6 The horizontal axis is the degree of image distortion, and its unit is percentage. Figure 6 The vertical coordinate is the field of view in the positive direction of the Y axis, and its unit is degree. Figure 6 It can be seen that the maximum distortion of the infrared optical lens is 1.3%. Therefore, the distortion of the infrared optical lens is small, meeting the distortion requirements of the excellent imaging quality standard.

[0126] Example 2

[0127] Figure 7 The schematic diagram of the structure layout of the infrared optical lens in Example 2 is shown. Figure 7 The mid-infrared optical lens includes, in sequence from the object side A to the image side B along the optical axis S: an aperture 4, a first aspherical mirror, a super lens 2, a second aspherical mirror, a protective member 5 and a window material 6.

[0128] Table 4. Some parameters of infrared optical lens

[0129] System Parameters data Total optical length (TTL) 42.21mm Field of view (2ω) 13.41° F-number 1.18 Effective focal length 41.42mm Working band Long-wave infrared (8μm~12μm)

[0130] As can be seen from Table 4, the infrared optical lens in this embodiment has an operating band of 8μm to 12 microns, which meets the working requirements of the far-infrared band. The F number (aperture) of the infrared optical lens is 1.18, which can greatly increase the amount of light entering the infrared optical lens, and collect as much energy as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality. At the same time, the total optical length of the infrared optical lens is only 42.21 mm, which fully meets the requirements of the infrared optical lens for miniaturization and thinness, and is conducive to the control of its volume.

[0131] Starting from the object plane, along the optical axis S from the object side A to the image side B, each surface in the optical system is numbered, and the parameters of each surface are summarized to obtain the following Table 5.

[0132] Table 5. Parameters of various surfaces in the infrared optical lens provided in Example 2

[0133] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 0 Physical surface unlimited 1e6 - 1 Aperture unlimited -7.72 - 2 Aspheric 23.02 5.61 Sulfur 3 Aspheric 29.20 5.26 - 4 Metasurface unlimited 0.3 silicon 5 Spherical unlimited 11.14 - 6 Aspheric -36.60 2.51 Sulfur 7 Aspheric -41.22 15.72 - 8 Spherical unlimited 0.3 germanium 9 Spherical unlimited 0.5 - 10 Spherical unlimited 0.725 silicon 11 Spherical unlimited 0.14 - 12 Image plane unlimited - -

[0134] For each surface in Table 5, surface 0 is the object surface, and surface 1 is the surface of the aperture 4 close to the object side A. Surface 2 is the surface of the first aspheric lens 1 close to the object side A, and surface 3 is the surface of the first aspheric lens 1 away from the object side A. Surface 4 is the surface of the superlens 2 close to the object side A. Since the micro-nano structure is provided on the surface of the superlens 2 close to the object side A, it is recorded as a super surface, and surface 5 is the surface of the superlens 2 away from the object side A. Surface 6 is the surface of the second aspheric lens 3 close to the object side A, and surface 7 is the surface of the second aspheric lens 3 away from the object side A. Surface 8 is the surface of the protective member 5 close to the object side A, and surface 9 is the surface of the protective member 5 away from the object side A. Surface 10 is the surface of the window material 6 close to the object side A, and surface 11 is the surface of the window material 6 away from the object side A. Surface 12 is the image surface.

[0135] Please refer to Table 5. Since the focusing distance of the optical system in this embodiment is 1 km, the distance from the object plane 0 to the surface 1 is 1e6 (10 6) mm. The radius of curvature of surface 1 is infinite, so surface 1 is a plane. The distance between surface 1 and surface 2 is -7.72 mm. It should be noted that the negative sign in the distance -7.72 mm indicates that surface 1 is located behind surface 2 along the direction from object side A to image side B. The material between surface 1 and surface 2 is air. The radius of curvature of surface 2 is 23.02 mm, the distance between surface 2 and surface 3 is 5.61 mm, and the material between surface 2 and surface 3 is chalcogenide glass. The radius of curvature of surface 3 is 29.20 mm, the distance between surface 3 and surface 4 is 5.26 mm, and the material between surface 3 and surface 4 is air. The radius of curvature of surface 4 is infinite, so surface 4 is a plane. The distance between surface 4 and surface 5 is 0.3 mm, and the material between surface 4 and surface 5 is silicon. The radius of curvature of surface 5 is infinite, so surface 5 is a plane. The distance between surface 5 and surface 6 is 11.14 mm, and the material between surface 5 and surface 6 is air. The radius of curvature of surface 6 is -36.60 mm, the distance between surface 6 and surface 7 is 2.51 mm, and the material between surface 6 and surface 7 is chalcogenide glass. The radius of curvature of surface 7 is -41.22 mm, the distance between surface 7 and surface 8 is 15.72 mm, and the material between surface 7 and surface 8 is air. The radius of curvature of surface 8 is infinite, so surface 8 is a plane. The distance between surface 8 and surface 9 is 0.3 mm, and the material between surface 8 and surface 9 is germanium. The radius of curvature of surface 9 is infinite, so surface 9 is a plane. The distance between surface 9 and surface 10 is 0.5 mm, and the material between surface 9 and surface 10 is air. The radius of curvature of surface 10 is infinite, so surface 10 is a plane. The distance between surface 10 and surface 11 is 0.725 mm, and the material between surface 10 and surface 11 is silicon. The radius of curvature of surface 11 is infinite, so surface 11 is a plane. The distance between the surface 11 and the surface 12 is 0.14 mm, and the material between the surface 11 and the surface 12 is air.

[0136] Surface 2, surface 3, surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0137]

[0138] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis S direction; c is the surface curvature of the aspherical surface, c=1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D are the aspherical coefficients. The values ​​of k, A, B, C, D, etc. of surface 2, surface 3, surface 6 and surface 7 can be obtained from Table 6.

[0139] Table 6 Coefficients of various orders of even-order aspheric surfaces in the infrared optical lens provided in Example 2

[0140] Surface serial number K A B C D E F G 2 -8.11E-02 3.08E-07 7.08E-11 -8.32E-12 -5.18E-15 0 0 0 3 3.67E-02 -1.26E-06 -6.16E-09 -6.31E-12 2.90E-15 0 0 0 6 5.86E+00 1.04E-04 -5.07E-07 1.31E-08 -2.71E-11 -5.86E-13 2.53E-15 4.24E-18 7 6.00E-01 9.36E-05 -9.55E-08 3.93E-09 7.87E-11 2.61E-15 -1.10E-14 7.31E-17

[0141] See also Figures 8 to 10 , Figures 8 to 10 The MTF field of view curves of the infrared optical lens provided in the present application at 20° C., -40° C., and 80° C. are shown respectively. MTF is an important indicator used to describe the imaging quality of an optical system. The larger the MTF value, the better the imaging quality.

[0142] Figure 8 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at 20℃, the MTF of the infrared optical lens within the 4.93mm field of view is all greater than 0.29, so the infrared optical lens has better image quality. Among them, Figure 8 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0143] Fig. 9 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at -40℃, the MTF of the infrared optical lens within the 4.93mm field of view is all greater than 0.29, so the infrared optical lens has better image quality. Among them, Fig. 9 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0144] Fig.10 The sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency at -40℃, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency at -40℃ are listed. It can be seen from the above six curves that at 80℃, the MTF of the infrared optical lens within the 4.93mm field of view is always greater than 0.25, so the infrared optical lens has better image quality. Among them, Fig.10 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0145] comprehensive Figures 8 to 10 It can be seen that, taking the center of the field of view as an example, the MTF value of the sagittal curve S1 of the optical lens at 20°C at a spatial frequency of 10lp / mm is 0.84, the MTF value of the sagittal curve S1 of the optical lens at -40°C at a spatial frequency of 10lp / mm is 0.82, and the MTF value of the sagittal curve S1 of the optical lens at 80°C at a spatial frequency of 10lp / mm is 0.83. Therefore, at the same spatial frequency (10lp / mm), when the temperature changes from 20°C to -40°C or even 80°C, the MTF value of the infrared optical lens changes little. Similarly, at other spatial frequencies (42lp / mm, 21lp / mm), when the temperature changes from 20°C to -40°C or even 80°C, the MTF value of the infrared optical lens also changes little. Therefore, the imaging quality of the infrared optical lens provided in this embodiment is less affected by temperature.

[0146] Fig.11 The figure shows the field curvature of the infrared optical lens provided in this embodiment under different wavelengths of infrared light. Figure 5 The field curvatures L1, L2 and L3 of far-infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the meridional direction, and the field curvatures L4, L5 and L6 of far-infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the sagittal direction are shown respectively. Fig.11 The horizontal axis is the distance deviation between the actual focus of the light and the image plane, and its unit is millimeter. Fig.11 The vertical coordinate is the field of view along the positive direction of the Y axis, and its unit is degree.

[0147] Depend on Fig.11 It can be seen that the maximum value of the field curvature L1 of the far-infrared light with a wavelength of 8 microns in the meridional direction is 0.1172 mm, and the maximum value of the field curvature L4 of the far-infrared light with a wavelength of 8 microns in the sagittal direction is 0.00748 mm. The maximum value of the field curvature L2 of the far-infrared light with a wavelength of 10 microns in the meridional direction is 0.108 mm, and the maximum value of the field curvature L5 of the far-infrared light with a wavelength of 10 microns in the sagittal direction is 0.068 mm. The maximum value of the field curvature L3 of the far-infrared light with a wavelength of 12 microns in the meridional direction is 0.12 mm, and the maximum value of the field curvature L6 of the far-infrared light with a wavelength of 12 microns in the sagittal direction is 0.076 mm. Therefore, the maximum field curvature of the infrared optical lens is 0.12 mm, and the field curvature of the infrared optical lens is small, which meets the requirements for field curvature in the excellent imaging quality standard.

[0148] Fig.12 The distortion of the optical system provided by the present application under 8 micron, 10 micron and 12 micron wavelength infrared light is shown ( Fig.12 There are three curves in total, but the gaps between the three curves are very small, resulting in the three curves almost overlapping). Fig.12The horizontal axis is the degree of image distortion, and its unit is percentage. Fig.12 The middle vertical coordinate is the field of view in the positive direction of the Y axis. Therefore, the maximum distortion of the infrared optical lens is 1.6%. Therefore, the distortion of the infrared optical lens is small, meeting the distortion requirements of the excellent imaging quality standard.

[0149] Example 3

[0150] Fig.13 The schematic diagram of the structure layout of the infrared optical lens in Example 3 is shown. Fig.13 The mid-infrared optical lens includes, in sequence from the object side A to the image side B along the optical axis S: an aperture 4, a first aspherical mirror, a super lens 2, a second aspherical mirror, a protective member 5 and a window material 6.

[0151] Table 7. Some parameters of infrared optical lens

[0152]

[0153]

[0154] As can be seen from Table 7, the infrared optical lens in this embodiment has an operating band of 8μm to 12 microns, which meets the working requirements of the far-infrared band. The F number (aperture) of the infrared optical lens is 1.17, which can greatly increase the amount of light entering the infrared optical lens, and collect as much energy as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality. At the same time, the total optical length of the infrared optical lens is only 44.34 mm, which fully meets the requirements of the infrared optical lens for miniaturization and thinness, and is conducive to the control of its volume.

[0155] Starting from the object plane, along the optical axis S from the object side A to the image side B, each surface in the optical system is numbered, and the parameters of each surface are summarized to obtain the following Table 8.

[0156] Table 8. Parameters of various surfaces in the infrared optical lens provided in Example 3

[0157] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 0 Physical surface unlimited 1e6 - 1 Aperture unlimited -6.07 - 2 Aspheric 28.91 3.42 Sulfur 3 Aspheric 43.12 4.52 - 4 Metasurface unlimited 0.3 silicon 5 Spherical unlimited 27 - 6 Aspheric 21.78 2 Sulfur series 7 Aspheric 19.58 4.73 - 8 Spherical unlimited 0.3 germanium 9 Spherical unlimited 0.5 - 10 Spherical unlimited 0.725 silicon 11 Spherical unlimited 0.86 12 Image plane unlimited -

[0158] For each surface in Table 8, surface 0 is the object surface, and surface 1 is the surface of the aperture 4 close to the object side A. Surface 2 is the surface of the first aspheric lens 1 close to the object side A, and surface 3 is the surface of the first aspheric lens 1 away from the object side A. Surface 4 is the surface of the superlens 2 close to the object side A. Since the micro-nano structure is provided on the surface of the superlens 2 close to the object side A, it is recorded as a super surface, and surface 5 is the surface of the superlens 2 away from the object side A. Surface 6 is the surface of the second aspheric lens 3 close to the object side A, and surface 7 is the surface of the second aspheric lens 3 away from the object side A. Surface 8 is the surface of the protective member 5 close to the object side A, and surface 9 is the surface of the protective member 5 away from the object side A. Surface 10 is the surface of the window material 6 close to the object side A, and surface 11 is the surface of the window material 6 away from the object side A. Surface 12 is the image surface.

[0159] Please refer to Table 8 again. Since the focusing distance of the optical system in this embodiment is 1 km, the distance from the object plane 0 to the surface 1 is 1e6 (10 6) mm. The radius of curvature of surface 1 is infinite, so surface 1 is a plane. The distance between surface 1 and surface 2 is -6.07 mm. It should be noted that the negative sign in the distance -6.07 mm indicates that surface 1 is located behind surface 2 along the direction from object side A to image side B. The material between surface 1 and surface 2 is air. The radius of curvature of surface 2 is 28.91 mm, the distance between surface 2 and surface 3 is 3.42 mm, and the material between surface 2 and surface 3 is chalcogenide glass. The radius of curvature of surface 3 is 43.12 mm, the distance between surface 3 and surface 4 is 4.52 mm, and the material between surface 3 and surface 4 is air. The radius of curvature of surface 4 is infinite, so surface 4 is a plane. The distance between surface 4 and surface 5 is 0.3 mm, and the material between surface 4 and surface 5 is silicon. The radius of curvature of surface 5 is infinite, so surface 5 is a plane. The distance between surface 5 and surface 6 is 27 mm, and the material between surface 5 and surface 6 is air. The radius of curvature of surface 6 is 21.78 mm, the distance between surface 6 and surface 7 is 2 mm, and the material between surface 6 and surface 7 is chalcogenide glass. The radius of curvature of surface 7 is 19.58 mm, the distance between surface 7 and surface 8 is 4.73 mm, and the material between surface 7 and surface 8 is air. The radius of curvature of surface 8 is infinite, so surface 8 is a plane. The distance between surface 8 and surface 9 is 0.3 mm, and the material between surface 8 and surface 9 is germanium. The radius of curvature of surface 9 is infinite, so surface 9 is a plane. The distance between surface 9 and surface 10 is 0.5 mm, and the material between surface 9 and surface 10 is air. The radius of curvature of surface 10 is infinite, so surface 10 is a plane. The distance between surface 10 and surface 11 is 0.725 mm, and the material between surface 10 and surface 11 is silicon. The radius of curvature of surface 11 is infinite, so surface 11 is a plane. The distance between the surface 11 and the surface 12 is 0.86 mm, and the material between the surface 11 and the surface 12 is air.

[0160] Surface 2, surface 3, surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0161]

[0162] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis S direction; c is the curvature of the aspherical surface, c=1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D are the aspherical coefficients. The values ​​of k, A, B, C, D, etc. of surface 2, surface 3, surface 6 and surface 7 can be obtained from Table 9.

[0163] Table 9 Coefficients of various orders of even-order aspheric surfaces in the infrared optical lens provided in Example 3

[0164]

[0165]

[0166] See also Figures 14 to 16 , Figures 14 to 16 The MTF field of view curves of the infrared optical lens provided in the present application at 20° C., -40° C., and 80° C. are shown respectively. MTF is an important indicator used to describe the imaging quality of an optical system. The larger the MTF value, the better the imaging quality.

[0167] Fig.14 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at 20℃, the MTF of the infrared optical lens within the 4.93mm field of view is all greater than 0.3, so the infrared optical lens has better image quality. Among them, Fig.14 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0168] Fig.15 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at -40℃, the MTF of the infrared optical lens within the 4.93mm field of view is all greater than 0.3, so the infrared optical lens has better image quality. Among them, Fig.15 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0169] Fig.16 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at 80℃, the MTF of the infrared optical lens within the 4.93mm field of view is always greater than 0.25, so the infrared optical lens has better image quality. Among them, Fig.16The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0170] comprehensive Figures 14 to 16 It can be seen that, taking the center of the field of view as an example, the MTF value of the sagittal curve S1 of the optical lens at 20°C at a spatial frequency of 10lp / mm is 0.83, the MTF value of the sagittal curve S1 of the optical lens at -40°C at a spatial frequency of 10lp / mm is 0.83, and the MTF value of the sagittal curve S1 of the optical lens at 80°C at a spatial frequency of 10lp / mm is 0.81. Therefore, at the same spatial frequency (10lp / mm), when the temperature changes from 20°C to -40°C or even 80°C, the MTF value of the infrared optical lens changes little. Similarly, at other spatial frequencies (42lp / mm, 21lp / mm), when the temperature changes from 20°C to -40°C or even 80°C, the MTF value of the infrared optical lens also changes little. Therefore, the imaging quality of the infrared optical lens provided in this embodiment is less affected by temperature.

[0171] Fig.17 The figure shows the field curvature of the infrared optical lens provided in this embodiment under different wavelengths of infrared light. Figure 5 The field curvatures L1, L2 and L3 of far-infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the meridional direction, and the field curvatures L4, L5 and L6 of far-infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the sagittal direction are shown respectively. Fig.17 The horizontal axis is the distance deviation between the actual focus of the light and the image plane, and its unit is millimeter. Fig.17 The vertical coordinate is the field of view along the positive direction of the Y axis, and its unit is degree.

[0172] Depend on Fig.17 It can be seen that the maximum value of the field curvature L1 of the far-infrared light with a wavelength of 8 microns in the meridional direction is 0.03 mm, and the maximum value of the field curvature L4 of the far-infrared light with a wavelength of 8 microns in the sagittal direction is 0.01 mm. The maximum value of the field curvature L2 of the far-infrared light with a wavelength of 10 microns in the meridional direction is 0.04 mm, and the maximum value of the field curvature L5 of the far-infrared light with a wavelength of 10 microns in the sagittal direction is 0.012 mm. The maximum value of the field curvature L3 of the far-infrared light with a wavelength of 12 microns in the meridional direction is 0.0327 mm, and the maximum value of the field curvature L6 of the far-infrared light with a wavelength of 12 microns in the sagittal direction is 0.0212 mm. Therefore, the maximum field curvature of the infrared optical lens is 0.04 mm, and the field curvature of the infrared optical lens is small, which meets the requirements for field curvature in the excellent imaging quality standard.

[0173] Fig.18 The distortion of the optical system provided by the present application under 8 micron, 10 micron and 12 micron wavelength infrared light is shown ( Fig.18There are three curves in total, but the gaps between the three curves are very small, resulting in the three curves almost overlapping). Fig.18 The horizontal axis is the degree of image distortion, and its unit is percentage. Fig.18 The middle vertical coordinate is the field of view in the positive direction of the Y axis. Therefore, the maximum distortion of the infrared optical lens is 1.5%. Therefore, the distortion of the infrared optical lens is small, meeting the distortion requirements of the excellent imaging quality standard.

[0174] Example 4

[0175] Fig.19 The schematic diagram of the structure layout of the infrared optical lens in Example 4 is shown. Fig.19 The mid-infrared optical lens includes, in sequence from the object side A to the image side B along the optical axis S: a first aspherical mirror, an aperture 4, a super lens 2, a second aspherical mirror, a protective member 5 and a window material 6.

[0176] Table 10. Some parameters of infrared optical lens

[0177] System Parameters data Total optical length (TTL) 44.05mm Field of view (2ω) 13.41° F-number 1.16 Effective focal length 41.25mm Working band Long-wave infrared (8μm~12μm)

[0178] As can be seen from Table 10, the infrared optical lens in this embodiment has an operating band of 8 to 12 microns, which meets the working requirements of the far-infrared band. The F number (aperture) of the infrared optical lens is 1.16, which can greatly increase the amount of light entering the infrared optical lens, and collect as much energy as possible when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality. At the same time, the total optical length of the infrared optical lens is only 44.05 mm, which fully meets the requirements of the infrared optical lens for miniaturization and thinness, and is conducive to the control of its volume.

[0179] Starting from the object plane, along the optical axis S from the object side A to the image side B, each surface in the optical system is numbered, and the parameters of each surface are summarized to obtain the following Table 11.

[0180] Table 11. Parameters of various surfaces in the infrared optical lens provided in Example 4

[0181] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 0 Physical surface unlimited 1e6 - 1 Aspheric 25.09 4.37 Sulfur series 2 Aspheric 34.18 4.23 - 3 Aperture unlimited 0.1 - 4 Metasurface unlimited 0.3 silicon 5 Spherical unlimited 15.07 - 6 Aspheric -20.31 2.54 Sulfur 7 Aspheric -21.81 9.28 - 8 Spherical unlimited 0.3 germanium 9 Spherical unlimited 0.5 - 10 Spherical unlimited 0.725 silicon 11 Spherical unlimited 7.04 12 Image plane unlimited -

[0182] For each surface in Table 11, surface 0 is the object surface, surface 1 is the surface of the first aspheric lens 1 close to the object side A. Surface 2 is the surface of the first aspheric lens 1 away from the object side A, and surface 3 is the surface of the aperture 4 close to the object side A. Surface 4 is the surface of the superlens 2 close to the object side A. Since the micro-nano structure is provided on the surface of the superlens 2 close to the object side A, it is recorded as a super surface, and surface 5 is the surface of the superlens 2 away from the object side A. Surface 6 is the surface of the second aspheric lens 3 close to the object side A, and surface 7 is the surface of the second aspheric lens 3 away from the object side A. Surface 8 is the surface of the protective member 5 close to the object side A, and surface 9 is the surface of the protective member 5 away from the object side A. Surface 10 is the surface of the window material 6 close to the object side A, and surface 11 is the surface of the window material 6 away from the object side A. Surface 12 is the image surface.

[0183] Please refer to Table 11. Since the focusing distance of the optical system in this embodiment is 1 km, the distance from the object plane 0 to the surface 1 is 1e6 (10 6 ) mm. The radius of curvature of surface 1 is 25.09, the distance between surface 1 and surface 2 is 4.37 mm, and the material between surface 1 and surface 2 is chalcogenide glass. The radius of curvature of surface 2 is 34.18 mm, the distance between surface 2 and surface 3 is 4.23 mm, and the material between surface 2 and surface 3 is air. The radius of curvature of surface 3 is infinite, so surface 3 is a plane. The distance between surface 3 and surface 4 is 0.1 mm, and the material between surface 3 and surface 4 is air. The radius of curvature of surface 4 is infinite, so surface 4 is a plane. The distance between surface 4 and surface 5 is 0.3 mm, and the material between surface 4 and surface 5 is silicon. The radius of curvature of surface 5 is infinite, so surface 5 is a plane. The distance between surface 5 and surface 6 is 15.07 mm, and the material between surface 5 and surface 6 is air. The radius of curvature of surface 6 is -20.31 mm, the distance between surface 6 and surface 7 is 2.54 mm, and the material between surface 6 and surface 7 is chalcogenide glass. The radius of curvature of surface 7 is -21.81 mm, the distance between surface 7 and surface 8 is 9.28 mm, and the material between surface 7 and surface 8 is air. The radius of curvature of surface 8 is infinite, so surface 8 is a plane. The distance between surface 8 and surface 9 is 0.3 mm, and the material between surface 8 and surface 9 is germanium. The radius of curvature of surface 9 is infinite, so surface 9 is a plane. The distance between surface 9 and surface 10 is 0.5 mm, and the material between surface 9 and surface 10 is air. The radius of curvature of surface 10 is infinite, so surface 10 is a plane. The distance between surface 10 and surface 11 is 0.725 mm, and the material between surface 10 and surface 11 is silicon. The radius of curvature of surface 11 is infinite, so surface 11 is a plane. The distance between the surface 11 and the surface 12 is 7.04 mm, and the material between the surface 11 and the surface 12 is air.

[0184] Surface 1, surface 2, surface 6 and surface 7 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0185]

[0186] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis S direction; c is the curvature of the aspherical surface, c=1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D are the aspherical coefficients. The values ​​of k, A, B, C, D, etc. of surface 2, surface 3, surface 6 and surface 7 can be obtained from Table 12.

[0187] Table 12. Coefficients of the even-order aspheric surfaces in the infrared optical lens provided in Example 4

[0188] Surface serial number K A B C D E F G 1 -9.31E-02 -1.94E-07 -1.09E-09 -2.06E-12 -1.78E-14 0 0 0 2 -1.42E-01 -8.86E-07 -5.55E-09 -2.20E-12 -4.26E-15 -3.77E-13 -1.41E-15 1.86E-17 6 1.57E-01 6.00E-05 3.24E-07 3.83E-09 1.39E-11 5.71E-13 -1.34E-14 6.45E-17 7 2.16E-01 5.99E-05 3.51E-07 1.82E-10 3.40E-11 -3.77E-13 -1.31E-15 1.86E-17

[0189] See also Figure 20 to Figure 22 , Figure 20 to Figure 22 The MTF field of view curves of the infrared optical lens provided in this embodiment at 20° C., -40° C., and 80° C. are respectively shown. MTF is an important indicator for describing the imaging quality of an optical system. The larger the MTF value, the better the imaging quality.

[0190] Fig. 20 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at 20℃, the MTF of the infrared optical lens within the 4.93mm field of view is always greater than 0.3, so the infrared optical lens has better image quality. Among them, Fig. 20 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0191] Fig.21 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at -40℃, the MTF of the infrared optical lens within the 4.93mm field of view is almost always greater than 0.3, so the infrared optical lens has better image quality. Among them, Fig.21The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0192] Fig. 22 The following table lists the sagittal curve S1 and meridional curve T1 of the MTF of the infrared optical lens at 42lp / mm spatial frequency as the field of view changes, the sagittal image curve S2 and meridional curve T2 of the MTF of the 21lp / mm spatial frequency as the field of view changes, and the sagittal image curve S3 and meridional curve T3 of the MTF of the 10lp / mm spatial frequency as the field of view changes. It can be seen from the above six curves that at 80℃, the MTF of the infrared optical lens within the 4.93mm field of view is always greater than 0.25, so the infrared optical lens has better image quality. Among them, Fig. 22 The Y field of view represents the field of view in the Y-axis direction, which is measured by image height in millimeters.

[0193] comprehensive Figure 20 to Figure 22 It can be seen that, taking the center of the field of view as an example, the MTF value of the sagittal curve S1 of the optical lens at 20°C at a spatial frequency of 10lp / mm is 0.83, the MTF value of the sagittal curve S1 of the optical lens at -40°C at a spatial frequency of 10lp / mm is 0.82, and the MTF value of the sagittal curve S1 of the optical lens at 80°C at a spatial frequency of 10lp / mm is 0.83. Therefore, at the same spatial frequency (10lp / mm), when the temperature changes from 20°C to -40°C or even 80°C, the MTF value of the infrared optical lens changes little. Similarly, at other spatial frequencies (42lp / mm, 21lp / mm), when the temperature changes from 20°C to -40°C or even 80°C, the MTF value of the infrared optical lens also changes little. Therefore, the imaging quality of the infrared optical lens provided in this embodiment is less affected by temperature.

[0194] Fig.23 The field curvature of the optical system provided by the present application under different wavelengths of infrared light is shown. Figure 5 The field curvatures L1, L2 and L3 of far-infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the meridional direction, and the field curvatures L4, L5 and L6 of far-infrared light with wavelengths of 8 microns, 10 microns and 12 microns in the sagittal direction are shown respectively. Fig.23 The horizontal axis is the distance deviation between the actual focus of the light and the image plane, and its unit is millimeter. Fig.23 The vertical coordinate is the field of view along the positive direction of the Y axis, and its unit is degree.

[0195] Depend on Fig.23It can be seen that the maximum value of the field curvature L1 of the far-infrared light with a wavelength of 8 microns in the meridional direction is 0.032 mm, and the maximum value of the field curvature L4 of the far-infrared light with a wavelength of 8 microns in the sagittal direction is 0.048 mm. The maximum value of the field curvature L2 of the far-infrared light with a wavelength of 10 microns in the meridional direction is 0.04 mm, and the maximum value of the field curvature L5 of the far-infrared light with a wavelength of 10 microns in the sagittal direction is 0.056 mm. The maximum value of the field curvature L3 of the far-infrared light with a wavelength of 12 microns in the meridional direction is 0.044 mm, and the maximum value of the field curvature L6 of the far-infrared light with a wavelength of 12 microns in the sagittal direction is 0.048 mm. Therefore, the maximum field curvature of the infrared optical lens is 0.056 mm, and the field curvature of the infrared optical lens is small, which meets the requirements for field curvature in the excellent imaging quality standard.

[0196] Fig.24 The distortion of the optical system provided by the present application under 8 micron, 10 micron and 12 micron wavelength infrared light is shown ( Fig.24 There are three curves in total, but the gaps between the three curves are very small, resulting in the three curves almost overlapping). Fig.24 The horizontal axis is the degree of image distortion, and its unit is percentage. Fig.24 The middle vertical coordinate is the field of view in the positive direction of the Y axis. Therefore, the maximum distortion of the infrared optical lens is 1.5%. Therefore, the distortion of the infrared optical lens is small, meeting the distortion requirements of the excellent imaging quality standard.

[0197] After summarizing the various parameters of the infrared optical lenses provided in the above four embodiments, the following Table 13 is obtained. Table 13 is mainly used to illustrate that the various conditions satisfied by the infrared optical lens provided in this application are all verified and supported by experiments.

[0198] Table 13. Parameters of infrared optical lenses provided in various embodiments

[0199]

[0200] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the utility model disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. An infrared optical system, characterized in that: The infrared optical system comprises, in order from the object side to the image side along the optical axis: a first aspheric lens, a super lens, and a second aspheric lens; the first aspheric lens is a positive lens, the surface of the first aspheric lens close to the image side is convex to the object side, and the surface of the first aspheric lens away from the image side is convex to the object side; the super lens is a positive lens; the second aspheric lens has an inflection point, and the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex to the image side or the object side; Wherein, when the surface of the second aspheric lens close to the object side and the surface far from the object side are both convex toward the object side, the second aspheric lens is a negative lens.

2. The infrared optical system according to claim 1, characterized in that: The infrared optical system satisfies the following conditional formula: Wherein, f is the effective focal length of the infrared optical system, t is the temperature; n a1 is the refractive index of the first aspheric lens, the f a1 is the focal length of the first aspheric lens; a2 is the refractive index of the second aspheric lens, the f a2 is the focal length of the second aspheric lens.

3. The infrared optical system according to claim 1, characterized in that: The infrared optical system satisfies the following conditional formula: Wherein, f is the effective focal length of the infrared optical system, and TTL is the total optical length of the infrared optical system.

4. The infrared optical system according to claim 1, characterized in that: The infrared optical system satisfies the following conditional formula: Wherein, the BFL is the optical back focus of the infrared optical system, and the TTL is the total optical length of the infrared optical system.

5. The infrared optical system according to claim 1, characterized in that: The infrared optical system satisfies the following conditional formula: Among them, the f m1 is the focal length of the superlens, and f is the effective focal length of the infrared optical system.

6. The infrared optical system according to claim 1, characterized in that: The infrared optical system satisfies the following conditional formula: Among them, the f a1 is the focal length of the first aspheric lens, and the f a2 is the focal length of the second aspheric lens.

7. The infrared optical system according to claim 1, characterized in that: The infrared optical system satisfies the following conditional formula: Wherein, f is the effective focal length of the infrared optical system, and D is the entrance pupil diameter of the infrared optical system.

8. The infrared optical system according to any one of claims 1 to 7, characterized in that: The infrared optical system further includes an aperture, and the aperture is disposed on the surface of the first aspheric lens, or the aperture is spaced apart from the first aspheric lens.

9. The infrared optical system according to any one of claims 1 to 7, characterized in that: When the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex toward the image side, the second aspheric lens is a positive lens, and the surface of the second aspheric lens away from the object side has at least one inflection point.

10. The infrared optical system according to any one of claims 1 to 7, characterized in that: When the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex toward the image side, the second aspheric lens is a negative lens, and the surface of the second aspheric lens away from the object side has at least one inflection point.

11. The infrared optical system according to any one of claims 1 to 7, characterized in that: When the surface of the second aspheric lens close to the object side and the surface away from the object side are both convex toward the object side, the surface of the second aspheric lens close to the object side has at least one inflection point.

12. An infrared optical lens, characterized in that: It comprises an imaging detector and the infrared optical system as described in any one of claims 1 to 11; the imaging detector is arranged on the image plane of the infrared optical system.

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