Infrared optical system and infrared optical lens

Abstract

The utility model provides an infrared optical system. The infrared optical system sequentially comprises a first refractor, a super lens and a second refractor from an object side to an image side along an optical axis, the focal power of the first refractor, the super lens and the second refractor is positive; the object side surface of the first refractor is convex towards the object side, and the image side surface of the first refractor is convex towards the object side; any one of the first refraction lens and the second refraction lens is an aspheric lens, and the other one of the first refraction lens and the second refraction lens is a spherical lens; the infrared optical system meets the following conditions: 1 < = fl1 / fl2 < = 10, fl1 is the focal length of the first refraction lens, fl2 is the focal length of the second refraction lens, the second refraction lens in the infrared optical system bears main focal power, lens tolerance sensitivity caused by overlarge focal power of the second refraction lens is avoided, and the imaging quality is improved while the high imaging quality is ensured. The number of used aspheric lenses is small, and the system size is relatively small.

Description

Technical Field

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

[0002] Infrared optical systems use infrared light radiated by objects to form images, and can form clear images at night or in harsh environments. Therefore, they are widely used in many fields such as security monitoring, medical equipment, automotive night vision, communication detection, consumer electronics, etc. The infrared optical systems provided by the prior art usually use multiple aspheric lenses including germanium lenses, which have the problems of difficult lens processing, high cost, and excessive total length of the optical system. There is a need to reduce the system size and production cost while ensuring the imaging quality. Utility Model Content

[0003] In order to solve the above technical problems, the present application provides an infrared optical system and an infrared optical lens, which reduce the number of aspheric lenses used and the system size while meeting high imaging quality, help achieve lightweight and miniaturization, and reduce production costs.

[0004] A first aspect of an embodiment of the present application provides an infrared optical system, which includes, in order from the object side to the image side along the optical axis: a first refractive lens, a super lens, and a second refractive lens; the optical powers of the first refractive lens, the super lens, and the second refractive lens are all positive; the object side surface of the first refractive lens is convex to the object side, and the image side surface of the first refractive lens is convex to the object side; any one of the first refractive lens and the second refractive lens is an aspherical lens, and the other of the first refractive lens and the second refractive lens is a spherical lens;

[0005] Among them, the infrared optical system meets the following requirements: f l1 is the focal length of the first refractive lens, f l2 is the focal length of the second refractive lens.

[0006] Optionally, the first refractive lens is a spherical lens, the second refractive lens is an aspherical lens, the object side surface of the second refractive lens is convex toward the image side, and the image side surface of the second refractive lens is convex toward the image side.

[0007] Optionally, the first refractive lens is an aspherical lens, the second refractive lens is a spherical lens, the object side surface of the second refractive lens is convex toward the object side, and the image side surface of the second refractive lens is convex toward the image side.

[0008] Optionally, the infrared optical system satisfies:

[0009]

[0010] Where f is the effective focal length of the infrared optical system, and EPD is the entrance pupil diameter of the infrared optical system.

[0011] Optionally, the infrared optical system satisfies:

[0012]

[0013] Among them, BFL is the optical back focal length of the infrared optical system, and TTL is the total optical length of the infrared optical system.

[0014] Optionally, the infrared optical system satisfies:

[0015]

[0016] Among them, f m is the focal length of the metalens, and f is the effective focal length of the infrared optical system.

[0017] Optionally, the infrared optical system satisfies:

[0018]

[0019] Among them, T l2 is the center thickness of the second refractive lens, n l2 is the material refractive index of the second refractive lens, c l21 is the curvature of the intersection of the object side surface of the second refractive lens and the optical axis, c l22 is the curvature of the intersection of the image side surface of the second refractive lens and the optical axis.

[0020] Optionally, the infrared optical system satisfies:

[0021]

[0022] Among them, EPD is the entrance pupil diameter of the infrared optical system, F# is the aperture number of the infrared optical system, and D l1 is the effective diameter of the first refractive lens, D l2 is the effective diameter of the second refractive lens.

[0023] Optionally, the infrared optical system satisfies:

[0024]

[0025] Among them, FOV is the maximum full field of view of the infrared optical system, R l11 is the radius of curvature of the intersection of the object side of the first refractive lens and the optical axis, R l12 is the radius of curvature of the intersection of the image side surface of the first refractive lens and the optical axis, T l1 is the central thickness of the first refractive lens.

[0026] Optionally, the infrared optical system satisfies:

[0027]

[0028] Among them, T a1 is the thickness of the central air gap between the first refractive lens and the superlens on the optical axis, T a2 is the thickness of the central air gap between the metalens and the second refractive lens on the optical axis, D l12 is the effective diameter of the image side of the first refractive lens, D l21 is the effective diameter of the object side of the second refractive lens, R l12 is the radius of curvature of the intersection of the image side surface of the first refractive lens and the optical axis, R l21 is the radius of curvature of the intersection of the object side surface of the second refractive lens and the optical axis.

[0029] Optionally, the infrared optical system further includes an aperture, which is disposed on the object side of the first refractive lens; or, disposed between the first refractive lens and the super lens; or, disposed between the super lens and the second refractive lens.

[0030] Optionally, the aperture is disposed between the first refractive lens and the superlens.

[0031] Another aspect of an embodiment of the present application provides an infrared optical lens, including an imaging detector and an infrared optical system, wherein the imaging detector is arranged on an image plane of the infrared optical system.

[0032] The infrared optical system provided according to the embodiment of the present application includes, in order from the object side to the image side along the optical axis: a first refractive lens, a super lens, and a second refractive lens, the optical focal lengths of the first refractive lens, the super lens, and the second refractive lens are all positive, the object side surface of the first refractive lens is convex to the object side, the image side surface of the first refractive lens is convex to the object side, any one of the first refractive lens and the second refractive lens is an aspherical lens, and the other of the first refractive lens and the second refractive lens is a spherical lens, wherein the infrared optical system satisfies: f l1 is the focal length of the first refractive lens, f l2 is the focal length of the second refractive lens. In the infrared optical system, the second refractive lens bears the main optical focal length and avoids the second refractive lens being sensitive to lens tolerance due to excessive optical focal length. While ensuring high imaging quality, the number of aspheric lenses used is small and the system size is relatively small. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown;

[0035] Figure 2 The MTF field of view curve diagram of the infrared optical system in one embodiment of the present application is shown;

[0036] Figure 3 A field curvature curve diagram of an infrared optical system in one embodiment of the present application is shown;

[0037] Figure 4 shows a distortion curve diagram of an infrared optical system in one embodiment of the present application;

[0038] Figure 5 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown;

[0039] Figure 6 The MTF field of view curve diagram of the infrared optical system in one embodiment of the present application is shown;

[0040] Figure 7 A field curvature curve diagram of an infrared optical system in one embodiment of the present application is shown;

[0041] Figure 8 shows a distortion curve diagram of an infrared optical system in one embodiment of the present application;

[0042] Fig. 9 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown;

[0043] Fig.10 The MTF field of view curve diagram of the infrared optical system in one embodiment of the present application is shown;

[0044] Fig.11 A field curvature curve diagram of an infrared optical system in one embodiment of the present application is shown;

[0045] Fig.12 A distortion curve diagram of an infrared optical system in an embodiment of the present application is shown.

[0046] List of reference numerals:

[0047] 10-first refractive lens, 20-super lens, 30-second refractive lens, 40-aperture, 50-window glass, 90-optical axis. DETAILED DESCRIPTION

[0048] The present application will now be described more fully below with reference to the accompanying drawings, in which various embodiments are shown. However, the present application can be implemented in many different ways and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present application will be exhaustive and complete, and will fully convey the scope of the present application to those skilled in the art. The same reference numerals throughout the text represent the same components. Furthermore, in the accompanying drawings, the thickness, ratios, and sizes of the components are exaggerated for clarity.

[0049] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, "one", "the", "at least one" as used herein do not represent a limitation on quantity, but are intended to include both the singular and the plural. For example, unless the context clearly indicates otherwise, "a component" has the same meaning as "at least one component". "At least one" should not be interpreted as being limited to the number "one". "Or" means "and / or". The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0050] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art. Terms defined in commonly used dictionaries should be interpreted as having the same meanings as in the relevant technical context, and unless clearly defined in the specification, these terms are not interpreted as having formal meanings in an idealized or overly formal sense.

[0051] The meaning of “include” or “comprising” specifies properties, quantities, steps, operations, components, parts or a combination thereof, but does not exclude other properties, quantities, steps, operations, components, parts or a combination thereof.

[0052] Embodiments are described herein with reference to cross-sectional views as idealized embodiments. Thus, variations in shape relative to the illustrated diagram are anticipated as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as shown herein, but should include deviations in shape due to, for example, manufacturing. For example, a region shown or described as flat may typically have rough and / or nonlinear features. Moreover, the sharp angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the claims.

[0053] In the related art, if the optical system inside the infrared optical lens needs to ensure the imaging quality, it is inevitable to use multiple aspherical refractive lenses including germanium lenses, which leads to a significant increase in the total optical length of the optical system as the number of refractive lenses increases. This will also significantly increase the volume, weight and cost of the infrared optical system. This feature of the related art obviously does not meet the current demand for miniaturization and lightweighting of optical devices.

[0054] In order to overcome the above-mentioned defects, the present application proposes an infrared optical system and an infrared optical lens.

[0055] Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of an infrared optical system provided by an embodiment of the present application, wherein Figure 1 In the figure, the object to be measured is located on the left side of the leftmost lens, that is, the object side is located on the left side of the leftmost lens, and the object plane is located on the object side. The image formed by the far-infrared optical system is located on the right side of the rightmost lens, that is, the image side is located on the right side of the rightmost lens, and the image plane is located on the image side. The infrared optical system includes a first refractive lens 10, a super lens 20, and a second refractive lens 30, which are arranged in sequence from the object side to the image side along the optical axis 90.

[0056] The optical power of the first refractive lens 10 is positive, the object side surface of the first refractive lens 10 is convex toward the object side, and the image side surface of the first refractive lens 10 is convex toward the object side. Specifically, the first refractive lens 10 is a meniscus lens with a convex surface facing the object side, which can effectively deflect the light beam into the infrared optical system, and the incident angles of the light on the object side surface and the image side surface of the first refractive lens 10 are both small, which is conducive to reducing the aberration of the infrared optical system.

[0057] The optical focal length of the superlens 20 is positive. The superlens 20 includes a substrate 210 and a micro-nano structure 220. According to the phase modulation method adopted, the corresponding phase modulation formula can be adaptively used to configure various parameters of the micro-nano structure 220, so that the superlens 20 can achieve corresponding optical performance.

[0058] The second refractive lens 30 has a positive optical power, the image side surface of the second refractive lens 30 is convex toward the image side, and the object side surface of the second refractive lens 30 is convex toward the object side or the image side. Any one of the first refractive lens 10 and the second refractive lens 30 is an aspherical lens, and the other one of the first refractive lens 10 and the second refractive lens 30 is a spherical lens.

[0059] Among them, the infrared optical system also meets the following conditions:

[0060]

[0061] Among them, f l1 is the focal length of the first refractive lens 10, f l2 is the focal length of the second refractive lens 30, f l1 and f l2 The dimensions of are the same, both are length units, such as millimeters. It should be noted that the first refractive lens 10 plays the role of collecting light beams entering the infrared optical system. When the optical focal length of the second refractive lens 30 is large, the curvature radius of the second refractive lens 30 will be large, resulting in processing difficulties. In the embodiment of the present application and various optional embodiments, f l1 / f l2 The lower limit of f is set to 1, so that the second refractive lens 30 bears the main optical focal length of the infrared optical system, which is beneficial to the effective focusing of the light beam. l1 / f l2 The upper limit is configured as 10, which can ensure that the first refractive lens 10 has a reasonable optical focal length. While achieving the function of collecting light beams, it can also avoid the second refractive lens 30 being sensitive to lens tolerance due to excessive optical focal length.

[0062] In the present application, the infrared optical system uses a mixture of refractive lenses and super lenses, which can ensure high imaging quality while using fewer aspheric lenses, thereby reducing lens costs and thus reducing production costs, while also reducing system size, helping to achieve lightweight and miniaturization.

[0063] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0064]

[0065] This can further ensure that the first refractive lens 10 has a reasonable optical focal length to achieve the function of collecting light beams, and also prevent the second refractive lens 30 from being too sensitive to lens tolerance due to excessive optical focal length.

[0066] In a preferred embodiment, the micro-nano structure 220 is disposed on the object side of the substrate 210, and the micro-nano structure 220 is a negative micro-nano structure, and the micro-nano structure 220 has only one layer. It should be noted that this is only an exemplary description and cannot be understood as a limitation on the superlens 20.

[0067] In an optional embodiment, the micro-nano structure 220 is only disposed on the object-side surface of the substrate 210 .

[0068] In an optional embodiment, the micro-nano structure 220 is only disposed on the image side of the substrate 210 .

[0069] In an optional embodiment, the object-side surface of the substrate 210 and the image-side surface of the substrate 210 are both provided with the micro-nano structure 220 .

[0070] In an optional embodiment, the micro-nano structure 220 is a positive micro-nano structure.

[0071] In an optional embodiment, the micro-nano structure 220 is a negative micro-nano structure.

[0072] In an optional embodiment, the micro-nano structure 220 is provided with a layer to make the processing technology of the superlens 20 compatible with the existing semiconductor processing technology, which can facilitate the production of the superlens 20.

[0073] In an optional embodiment, the micro-nano structure 220 is provided with two or more layers, so that the superlens 20 has a larger optical focal length that meets the expected requirements.

[0074] The position of the micro-nano structure 220 on the substrate 210, the positive and negative sides of the micro-nano structure 220, and the number of layers of the micro-nano structure 220 can be freely combined as long as the superlens 20 has the expected performance.

[0075] In the embodiment of the present application and each optional embodiment, the aspheric lens is mainly used to correct aberrations, which is conducive to obtaining higher imaging quality. In the embodiment of the present application and each optional embodiment, the aspheric lens is an even-order aspheric lens, and its surface shape meets the following conditions:

[0076]

[0077] Wherein, Z(r) is the distance vector height of the aspheric lens from the vertex of the aspheric lens when the aspheric lens is at a height of r in a direction parallel to the optical axis 90, c is the curvature of the aspheric lens, k is the cone coefficient, and A, B, C, and D correspond to the high-order coefficients of the aspheric lens, respectively. In the embodiment of the present application, the aspheric lens is an even-order aspheric lens, which is beneficial to saving materials and space, improving the tolerance of the optical system, reducing or eliminating reflections, and improving the performance of the optical system.

[0078] In an optional embodiment, the first refractive lens 10 is a spherical lens, the second refractive lens 30 is an aspherical lens, the object side of the second refractive lens 30 is convex to the image side, and the image side of the second refractive lens 30 is convex to the image side. Specifically, the second refractive lens 30 is a meniscus aspherical lens with a convex surface facing the image side, which can play a good light beam focusing effect.

[0079] In an optional embodiment, the first refractive lens 10 is an aspherical lens, the second refractive lens 30 is a spherical lens, the object side surface of the second refractive lens 30 is convex toward the object side, and the image side surface of the second refractive lens 30 is convex toward the image side. Specifically, the second refractive lens 30 is a biconvex spherical lens, which can play a good role in focusing the light beam.

[0080] In the embodiment of the present application and various optional embodiments, the metasurface phase distribution of the metalens 20 satisfies the following conditions:

[0081]

[0082] Where r is the distance from the center of the superlens 20 to any micro-nanostructure, λ is the operating wavelength of the superlens, is the phase constant, (x,y) is the mirror coordinate of the superlens, and f m is the focal length of the superlens 20, a i and b i are real coefficients.

[0083] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0084]

[0085] Among them, f is the effective focal length of the infrared optical system, and the dimension of f is the unit of length. EPD (Entrance Pupil Diameter, abbreviated as EPD) is the entrance pupil diameter of the infrared optical system, and the dimension of EPD is the unit of length. EPD and f have the same dimension, both are units of length, such as millimeters. Specifically, f / EPD is the aperture number of the infrared optical system, and the aperture is also called the F number. The F number is mainly used to control the amount of light entering the infrared optical system. It should be noted that when the value of f / EPD is too large, the amount of light entering the infrared optical system will be reduced, the utilization rate of light energy will be low, and then the imaging quality will be poor. When f / EPD≤1, it is beneficial to reduce the size of the system while meeting the requirements of imaging clarity and light intensity response, thereby ensuring excellent imaging quality.

[0086] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0087]

[0088] Among them, BFL is the optical back focal length of the infrared optical system. In the present application, BFL (Back focal length, referred to as BFL) is the distance from the image side of the second refractive lens 30 to the image plane of the infrared optical system, TTL (Total Track Length, referred to as TTL) is the total optical length of the infrared optical system. In the present application, TTL is the distance from the object side of the first refractive lens 10 to the image plane of the infrared optical system. The dimensions of BFL and TTL are length units. In the embodiment of the present application and each optional embodiment, the upper limit of the range of BFL / TTL is set to 0.40, which can avoid the effective diameter of the second refractive lens 30 being too large, and then the volume of the second refractive lens 30 being too large, which is beneficial to reducing the mass of the infrared optical system. Setting the lower limit of the range of BFL / TTL to 0.35 can ensure that the infrared optical system has a suitable optical back focal length, which is beneficial to the assembly of the infrared optical system.

[0089] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0090]

[0091] Among them, f m is the focal length of the superlens 20, f is the effective focal length of the infrared optical system, and f and f m The dimensions of are the same, both are length units, such as millimeters. It should be noted that in order to make the superlens 20 have a larger optical focal length, the superlens 20 needs a larger phase gradient, that is, there are higher requirements on the shape of the micro-nano structure 220 of the superlens 20. Therefore, the greater the optical focal length provided by the superlens 20 in the optical system, the more complex the processing of the micro-nano structure 220 of the superlens 20, which will cause a larger processing error for the superlens 20. In the embodiment of the present application and various optional embodiments, f m The upper limit of / f is set to 60, which can ensure that the superlens 20 provides a focal length that meets the preset requirements in the infrared optical system, which is beneficial to effectively reduce the aberration of the far-infrared optical system. m The lower limit of / f is configured to be 15, which can prevent the optical focal length of the superlens 20 from being too large, thereby controlling the processing error of the superlens 20 to a reasonable level.

[0092] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0093]

[0094] Among them, T l2 is the central thickness of the second refractive lens 30, that is, the thickness of the second refractive lens 30 on the optical axis 90, n l2 is the material refractive index of the second refractive lens 30, c l21 is the curvature of the intersection of the object side surface of the second refractive lens 30 and the optical axis 90, c l22 is the curvature of the intersection of the image side surface of the second refractive lens 30 and the optical axis 90, T l2 The dimension of the unit is length, c l21 and c l22 The dimensions are the same, which are all negative first powers of the units corresponding to their lengths, such as mm -1 In the present embodiment and various optional embodiments, T l2 (n l2 -1) / (c l21 -c l22 ) is configured to be less than 110mm 2, it is possible to prevent the center thickness of the second refractive lens 30 from being too large, thereby preventing the weight of the infrared optical system and the cost of lens materials from increasing, while ensuring that the second refractive lens 30 has sufficient optical power to effectively focus the light beam. l2 (n l2 -1) / (c l21 -c l22 ) is configured to be greater than 10mm 2 , it is possible to prevent the center thickness of the second refractive lens 30 from being too small, thereby preventing the second refractive lens 30 from being difficult to process.

[0095] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0096]

[0097] Among them, EPD is the entrance pupil diameter of the infrared optical system, F# is the aperture number of the infrared optical system, and D l1 D is the effective diameter of the first refractive lens 10. In the present application, the effective diameter is the diameter of the maximum light transmission area of ​​the lens. l2 is the effective diameter of the second refractive lens 30, TTL is the total optical length of the infrared optical system, EPD, D l1 , D l2 The dimensions of TTL are the same, both are length units, such as millimeters. In the present embodiment and various optional embodiments, (D l1 *EPD*F#) / (D l2 *TTL) is set to less than 32 to prevent the effective diameter of the first refractive lens 10 from being too large, thereby preventing the infrared optical system from being too large, which is beneficial to reducing the volume of the infrared optical system and the lens material cost, while meeting the focal length requirements of the lens corresponding to the infrared optical system. l1 *EPD*F#) / (D l2 * The lower limit of TTL is set to be greater than 21, which can avoid the infrared optical system being too large due to the total optical length TTL being too large, while ensuring that the lenses in the optical system are assembled in the same direction to reduce the assembly error.

[0098] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0099]

[0100] Among them, FOV (Field of View, referred to as FOV) is the maximum full field of view of the infrared optical system, R l11 is the radius of curvature of the intersection of the object side surface of the first refractive lens 10 and the optical axis, R l12is the curvature radius of the intersection of the image side surface of the first refractive lens 10 and the optical axis, T l1 is the center thickness of the first refractive lens 10, R l11 , R l12 and T l1 The dimensions of (FOV*R are the same, both are length units, such as millimeters. In the present embodiment and various optional embodiments, (FOV*R l11 2 ) / (R l12 *T l1 ) is set to less than 85°, which can avoid the increase of aberration and the enhancement of surface reflection caused by the excessive angle of the light incident on the first refractive lens 10. l11 2 ) / (R l12 *T l1 ) is set to be greater than 60°, which can simultaneously ensure that the first refractive lens 10 has a reasonable optical focal length to collect the light beam entering the infrared optical system, and the second refractive lens 30 bears the main optical focal length to reduce aberrations.

[0101] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0102]

[0103] Among them, T a1 is the thickness of the central air gap between the first refractive lens 10 and the super lens 20 on the optical axis, T a2 is the thickness of the central air gap between the super lens 20 and the second refractive lens 30 on the optical axis, D l12 is the effective diameter of the image side of the first refractive lens 10, D l21 is the effective diameter of the object side of the second refractive lens 30, R l12 is the curvature radius of the intersection of the image side surface of the first refractive lens 10 and the optical axis 90, R l21 is the curvature radius of the intersection of the object side surface of the second refractive lens 30 and the optical axis 90, T a1 、T a2 , D l12 , D l21 , R l12 and R l21 The dimensions of are the same, both are length units, such as millimeters. In the embodiment of the present application and various optional embodiments, the length of the object side surface of the first refractive lens 10 and the image side surface of the second refractive lens 30 on the optical axis is the main body length of the infrared optical system. a1 +T a2 -D l12 2 / 4R l12 +D l212 / 4R l21 The upper limit of T is set to less than 1.1 mm, which can limit the main length of the infrared optical system and avoid the infrared optical system being too large. a1 +T a2 -D l12 2 / 4R l12 +D l21 2 / 4R l21 The lower limit is set to be greater than 0.3 mm, which can avoid the edge air gap between the first refractive lens 10, the super lens 20 and the second refractive lens 30 being too small, resulting in the inability to use structural parts for reasonable positioning.

[0104] In an optional embodiment, the infrared optical system further includes an aperture 40, and the aperture 40 is mainly used to control the amount of light entering the infrared optical system.

[0105] In an optional embodiment, the aperture 40 is disposed on the object side of the first refractive lens 10 .

[0106] In an optional embodiment, the aperture 40 is disposed between the super lens 20 and the second refractive lens 30 .

[0107] In an optional embodiment, the aperture 40 is disposed between the first refractive lens 10 and the super lens 20 .

[0108] Preferably, the aperture 40 is disposed on the object side of the superlens 20 .

[0109] In an optional embodiment, a window glass 50 is provided on the image side of the second refractive lens 30 to protect the imaging detector of the infrared optical lens corresponding to the infrared optical system disposed on the image plane of the infrared optical system.

[0110] In an optional embodiment, the material of the window glass 50 is silicon.

[0111] The present application also provides an infrared optical lens, see Figure 1 The infrared optical lens includes the infrared optical system shown in any of the above embodiments, and an imaging detector arranged on the image plane of the infrared optical system. The detailed design of the optical system will not be described here.

[0112] Table 1. System parameters of infrared optical system

[0113] System Parameters data F-number ≤1 Total optical length (TTL) <11.6mm MTF at maximum field of view at 42cyc / mm frequency ＞0.33 System distortion ＜1.1％ Working band 8μm-12μm

[0114] Table 1 shows various system parameters of the infrared optical system provided in the embodiment of the present application. Specifically, the optical system to be provided is targeted to work in the far infrared band, i.e., the 8μm-12μm band; the F number is ≤1; the system distortion is <1.1%; the MTF at the frequency of 42cyc / mm under the maximum field of view is above 0.33; and the total optical length is <11.6mm.

[0115] Taking the system parameters shown in Table 1 as the target, in order to further describe the characteristics of the infrared optical system provided by the embodiments of the present application, the present application provides four embodiments that meet the constraints of the above conditional expressions as follows:

[0116] Example 1

[0117] Figure 1 FIG. 1 shows a schematic diagram of the infrared optical system architecture layout provided in this embodiment. Figure 1 In Example 1, the infrared optical system includes a first refractive lens 10, a super lens 20, a second refractive lens 30 and a window glass 50 which are sequentially arranged from the object side to the image side along the optical axis 90. The first refractive lens 10 is an aspherical lens, the second refractive lens 30 is a spherical lens, and the aperture 40 is arranged between the first refractive lens 10 and the super lens 20.

[0118] Table 2-1. System parameters of the infrared optical system provided in Example 1

[0119] parameter data Total optical length (TTL) 11.43mm Maximum field of view FOV 30.84° F-number 0.95 Effective focal length 7.0mm Working band 8μm-12μm

[0120] It can be seen from Table 2-1 that the infrared optical system in this embodiment has an F number of 0.95, which can increase the amount of light entering the optical system and collect as much energy entering the optical system as possible when the imaging detector has a low response to light energy, thereby ensuring excellent imaging quality; at the same time, the maximum field of view angle of the optical system is 30.84°, which ensures the requirements of the optical system for the field of view angle; at the same time, the total optical length is only 11.43mm, which fully meets the requirements of the optical system for miniaturization and thinness.

[0121] Each surface in the optical system is numbered from the object side to the image side, and the parameters such as the curvature radius, thickness and material of each lens surface in the optical system are summarized to obtain Table 2-2.

[0122] Table 2-2. Surface parameters of the infrared optical system provided in Example 1

[0123]

[0124]

[0125] Refer to Table 2-2, surface 0 is the object plane; the object plane is a spherical surface with infinite radius of curvature, that is, object plane 0 is a plane; since the distance between the object plane and the object side surface of the aspheric lens is not fixed, the distance between the two is recorded as infinite, and the material between the object plane and the object side surface of the aspheric lens is air. Surface 1 is the object side surface of the aspheric lens, with a radius of curvature of 5.50 mm, a distance between it and surface 2 of 2.65 mm, and a material between it and surface 2 of chalcogenide glass. Surface 2 is the image side surface of the aspheric lens, with a radius of curvature of 4.44 mm, a distance between it and surface 3 of 1.23 mm, and a material between it and surface 3 of air. Surface 3 is the aperture, and the radius of curvature of surface 3 is infinite, therefore, surface 3 is a plane, and the distance between it and surface 4 is 0.3 mm, and a material between it and surface 4 of air. Surface 4 is the object side of the metalens, and the radius of curvature of surface 4 is infinite. Therefore, surface 4 is a plane, and the distance between it and surface 5 is 0.3 mm, and the material between it and surface 5 is silicon. Surface 5 is the image side of the metalens, and the radius of curvature of surface 5 is infinite. Therefore, surface 5 is a plane, and the distance between it and surface 6 is 0.61 mm, and the material between it and surface 6 is air. Surface 6 is the object side of the spherical lens, and the radius of curvature of surface 6 is 67.46 mm, and the distance between it and surface 7 is 2.05 mm, and the material between it and surface 7 is chalcogenide glass. Surface 7 is the image side of the spherical lens, and the radius of curvature of surface 7 is -12.18 mm, and the distance between it and surface 8 is 3.50 mm, and the material between it and surface 8 is air. Surface 8 is the object side of the window glass, and the radius of curvature of surface 8 is infinite. Therefore, surface 8 is a plane, and the distance between it and surface 9 is 0.70 mm, and the material between it and surface 9 is silicon. Surface 9 is the image side of the window glass, and the curvature radius of surface 9 is infinite, so surface 9 is a plane, and the distance between it and the image plane is 0.10 mm, and the material between it and surface 10 is air. Surface 10 is the image plane, and the curvature radius of surface 10 is infinite, so surface 10 is a plane.

[0126] After summarizing the surface coefficients of aspheric refractive lenses, we obtain Table 2-3.

[0127] Table 2-3. Surface parameters of aspheric lens of infrared optical system provided in Example 1

[0128]

[0129] Figure 2 shows the MTF field of view curve of the infrared optical system provided in this embodiment, Figure 2 The horizontal axis in the middle is the Y field of view, which is measured by the image height. Figure 2 The vertical axis represents the MTF value. Figure 2As shown, the sagittal image curve S1 and the meridional image curve T1 of the MTF with the change of the field of view at the spatial frequency of 42cyc / mm, the sagittal image curve S2 and the meridional image curve T2 of the MTF with the change of the field of view at the spatial frequency of 21cyc / mm, and the sagittal image curve S3 and the meridional image curve T3 of the MTF with the change of the field of view at the spatial frequency of 10cyc / mm are listed respectively. It can be seen that the MTF of the infrared optical system within the Y field of view of 1.92mm is always greater than 0.37, which meets the requirements for MTF in the excellent imaging quality standard.

[0130] Figure 3 The infrared optical system provided in this embodiment shows the field curvature curve S1 in the sagittal direction and the field curvature curve T1 in the meridional direction at an operating wavelength of 8 μm; the field curvature curve S2 in the sagittal direction and the field curvature curve T2 in the meridional direction at an operating wavelength of 9 μm; the field curvature curve S3 in the sagittal direction and the field curvature curve T3 in the meridional direction at an operating wavelength of 10 μm; the field curvature curve S4 in the sagittal direction and the field curvature curve T4 in the meridional direction at an operating wavelength of 11 μm; and the field curvature curve S5 in the sagittal direction and the field curvature curve T5 in the meridional direction at an operating wavelength of 12 μm. The horizontal axis represents the field curvature, and its unit is millimeter. The vertical axis is the Y-axis field of view, and its unit is degree. Figure 3 It can be seen that the maximum field curvature of the infrared optical system provided in Example 1 in the sagittal direction is 0.0701 mm, and the maximum field curvature of the infrared optical system provided in Example 1 in the meridional direction is 0.0742 mm. It can be seen that the maximum field curvature of the infrared optical system provided in this embodiment is less than 0.08 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0131] Figure 4 The distortion curves of the infrared optical system provided in this embodiment at wavelengths of 8 μm, 9 μm, 10 μm, 11 μm and 12 μm are shown ( Figure 4 There are five curves shown in the whole, but the gaps between the five curves are very small, resulting in the five curves almost overlapping, so the five curves are not distinguished). Figure 4 The horizontal axis represents the degree of image distortion, and its unit is percentage. Figure 4 The middle vertical coordinate is the Y-axis field of view. It can be seen that the distortion of the infrared optical system provided by this embodiment is within -0.83%, which meets the distortion requirement of the excellent imaging quality standard.

[0132] Example 2

[0133] Figure 5 FIG. 1 shows a schematic diagram of the infrared optical system architecture layout provided in this embodiment. Figure 5In Example 2, the infrared optical system includes a first refractive lens 10, a super lens 20, a second refractive lens 30 and a window glass 50 which are sequentially arranged from the object side to the image side along the optical axis 90. The first refractive lens 10 is an aspherical lens, the second refractive lens 30 is a spherical lens, and the aperture 40 is arranged between the first refractive lens 10 and the super lens 20.

[0134] Table 3-1. System parameters of the infrared optical system provided in Example 2

[0135] parameter data Optical total length TTL 11.56mm Maximum field of view FOV 30.96° F-number 0.95 Effective focal length 7.06mm Working band 8μm-12μm

[0136] It can be seen from Table 3-1 that the infrared optical system in this embodiment has an F number of 0.95, which can increase the amount of light entering the optical system and collect as much energy entering the optical system as possible when the imaging detector has a low response to light energy, thereby ensuring excellent imaging quality; at the same time, the maximum field of view angle of the optical system is 30.96°, which ensures the requirements of the optical system for the field of view angle; at the same time, the total optical length is only 11.56 mm, which fully meets the requirements of the optical system for miniaturization and thinness.

[0137] Each surface in the optical system is numbered from the object side to the image side, and the parameters such as the radius, thickness, and material of each lens surface in the optical system are summarized to obtain Table 3-2.

[0138] Table 3-2. Surface parameters of the infrared optical system provided in Example 2

[0139] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 0 Physical surface unlimited unlimited - 1 Aspheric 6.36 3.30 Sulfur 2 Aspheric 4.82 2.03 - 3 Aperture unlimited 0.40 - 4 Metasurface unlimited 0.30 silicon 5 Spherical unlimited 0.10 - 6 Spherical 19.16 1.17 Sulfur series 7 Spherical -18.62 3.47 - 8 Spherical unlimited 0.70 silicon 9 Spherical unlimited 0.10 - 10 Image plane unlimited - -

[0140] For the analysis of each surface in Table 3-2, please refer to Table 2-2 of Example 1, which will not be repeated here.

[0141] After summarizing the surface coefficients of aspheric refractive lenses, we obtain Table 3-3.

[0142] Table 3-3. Surface parameters of aspheric lens of infrared optical system provided in Example 2

[0143] Surface serial number K A B C D E F G 1 -1.01 7.21E-04 -3.95E-05 4.61E-06 -4.20E-07 1.95E-08 -4.40E-10 0 2 -0.87 1.95E-03 2.63E-04 -1.01E-04 1.69E-05 -1.64E-05 5.80E-08 0

[0144] Figure 6 shows the MTF field of view curve of the infrared optical system provided in this embodiment, Figure 6 The horizontal axis in the middle is the Y field of view, which is measured by the image height. Figure 6 The vertical axis represents the MTF value. Figure 6As shown, the sagittal image curve S1 and the meridional image curve T1 of the MTF with the change of the field of view at the spatial frequency of 42cyc / mm, the sagittal image curve S2 and the meridional image curve T2 of the MTF with the change of the field of view at the spatial frequency of 21cyc / mm, and the sagittal image curve S3 and the meridional image curve T3 of the MTF with the change of the field of view at the spatial frequency of 10cyc / mm are listed respectively. It can be seen that the MTF of the infrared optical system within the Y field of view of 1.92mm is always greater than 0.34, which meets the requirements for MTF in the excellent imaging quality standard.

[0145] Figure 7 The infrared optical system provided in this embodiment shows the field curvature curve S in the sagittal direction and the field curvature curve T in the meridional direction at the working wavelengths of 8 μm, 9 μm, 10 μm, 11 μm and 12 μm respectively. Figure 7 A total of 10 curves are shown, but the differences between the sagittal field curvature curves and the meridional field curvature curves are extremely small, resulting in the five curves almost overlapping, so they are only distinguished as the sagittal field curvature curve S and the meridional field curvature curve T). The horizontal axis represents the field curvature, and its unit is millimeter. The vertical axis is the Y-axis field of view, and its unit is degree. Figure 7 It can be seen that the maximum field curvature of the infrared optical system provided in Example 2 in the sagittal direction is 0.1489 mm, and the maximum field curvature of the infrared optical system provided in Example 2 in the meridional direction is 0.1990 mm. It can be seen that the maximum field curvature of the infrared optical system provided in this embodiment is less than 0.2 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0146] Figure 8 The distortion curves of the infrared optical system provided in this embodiment at wavelengths of 8 μm, 9 μm, 10 μm, 11 μm and 12 μm are shown ( Figure 8 There are five curves shown in the whole, but the gaps between the five curves are very small, resulting in the five curves almost overlapping, so the five curves are not distinguished). Figure 8 The horizontal axis represents the degree of image distortion, and its unit is percentage. Figure 8 The middle vertical coordinate is the Y-axis field of view. It can be seen that the distortion of the infrared optical system provided by this embodiment is within ±0.6%, which meets the distortion requirement of the excellent imaging quality standard.

[0147] Example 3

[0148] Fig. 9 FIG. 1 shows a schematic diagram of the infrared optical system architecture layout provided in this embodiment. Fig. 9In Example 3, the infrared optical system includes a first refractive lens 10, a super lens 20, a second refractive lens 30 and a window glass 50 which are sequentially arranged from the object side to the image side along the optical axis 90. The first refractive lens 10 is a spherical lens, the second refractive lens 30 is an aspherical lens, and the aperture 40 is arranged on the object side of the super lens 20.

[0149] Table 4-1. System parameters of the infrared optical system provided in Example 3

[0150] parameter data Optical total length TTL 11.56mm Maximum field of view FOV 30.66° F-number 0.94 Effective focal length 6.98mm Working band 8μm-12μm

[0151] It can be seen from Table 4-1 that the infrared optical system in this embodiment has an F number of 0.94, which can increase the amount of light entering the optical system and collect as much energy entering the optical system as possible when the imaging detector has a low response to light energy, thereby ensuring excellent imaging quality; at the same time, the maximum field of view angle of the optical system is 30.66°, which ensures the requirements of the optical system for the field of view angle; at the same time, the total optical length is only 11.56 mm, which fully meets the requirements of the optical system for miniaturization and thinness.

[0152] Each surface in the optical system is numbered from the object side to the image side, and the parameters such as the radius, thickness, and material of each lens surface in the optical system are summarized to obtain Table 4-2.

[0153] Table 4-2. Surface parameters of the infrared optical system provided in Example 3

[0154]

[0155]

[0156] For the analysis of each surface in Table 4-2, please refer to Table 2-2 of Example 1, which will not be repeated here.

[0157] After summarizing the surface coefficients of aspheric refractive lenses, we obtain Table 4-3.

[0158] Table 4-3. Surface parameters of aspheric lens of infrared optical system provided in Example 3

[0159]

[0160] Fig.10 shows the MTF field of view curve of the infrared optical system provided in this embodiment, Fig.10 The horizontal axis in the middle is the Y field of view, which is measured by the image height. Fig.10 The vertical axis represents the MTF value. Fig.10As shown, the sagittal image curve S1 and the meridional image curve T1 of the MTF with the change of the field of view at the spatial frequency of 42cyc / mm, the sagittal image curve S2 and the meridional image curve T2 of the MTF with the change of the field of view at the spatial frequency of 21cyc / mm, and the sagittal image curve S3 and the meridional image curve T3 of the MTF with the change of the field of view at the spatial frequency of 10cyc / mm are listed respectively. It can be seen that the MTF of the infrared optical system within the Y field of view of 1.92mm is always greater than 0.33, which meets the requirements for MTF in the excellent imaging quality standard.

[0161] Fig.11 The infrared optical system provided in this embodiment shows the field curvature curve S1 in the sagittal direction and the field curvature curve T1 in the meridional direction at an operating wavelength of 8 μm; the field curvature curve S2 in the sagittal direction and the field curvature curve T2 in the meridional direction at an operating wavelength of 9 μm; the field curvature curve S3 in the sagittal direction and the field curvature curve T3 in the meridional direction at an operating wavelength of 10 μm; the field curvature curve S4 in the sagittal direction and the field curvature curve T4 in the meridional direction at an operating wavelength of 11 μm; and the field curvature curve S5 in the sagittal direction and the field curvature curve T5 in the meridional direction at an operating wavelength of 12 μm. The horizontal axis represents the field curvature, and its unit is millimeter. The vertical axis is the Y-axis field of view, and its unit is degree. Fig.11 It can be seen that the maximum field curvature of the infrared optical system provided in Example 3 in the sagittal direction is 0.0177 mm, and the maximum field curvature of the infrared optical system provided in Example 3 in the meridional direction is 0.0594 mm. It can be seen that the maximum field curvature of the infrared optical system provided in this embodiment is less than 0.06 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0162] Fig.12 The distortion curves of the infrared optical system provided in this embodiment at wavelengths of 8 μm, 9 μm, 10 μm, 11 μm and 12 μm are shown ( Fig.12 There are five curves shown in the whole, but the gaps between the five curves are very small, resulting in the five curves almost overlapping, so the five curves are not distinguished). Fig.12 The horizontal axis represents the degree of image distortion, and its unit is percentage. Fig.12 The middle vertical coordinate is the Y-axis field of view. It can be seen that the maximum distortion of the optical system is less than , therefore, the distortion of the infrared optical system provided by this embodiment is within 0.5%, meeting the distortion requirement of the excellent imaging quality standard.

[0163] After summarizing the lens parameters of the optical systems provided in the above three embodiments, the following Table 5 is obtained. Table 5 is mainly used to illustrate that the conditions satisfied by the optical system provided in this application are all verified and supported by experiments.

[0164] Table 5. Parameters of the optical system provided in each embodiment

[0165] Conditional Expressions Example 1 Example 2 Example 3 f 7.00mm 7.06mm 6.98mm TTL 11.43mm 11.56mm 11.56mm FOV 30.84° 30.96° 30.66° f / EPD 0.95 0.95 0.94 BFL / TTL 0.376 0.369 0.381 <![CDATA[f m / f]]> 36.50 29.90 53.92 <![CDATA[f l1 / f l2 ]]> 3.70 5.59 1.48 <![CDATA[(D l1 *EPD*F#) / (D l2 *TTL)]]> 25.46 29.67 23.14 <![CDATA[(FOV*R l11 2 ) / (R l12 *T l1 )]]> 79.46° 78.83° 67.04° <![CDATA[T l2 (n l2 -1) / (c l21 -c l22 )]]> <![CDATA[37.57mm 2 ]]> <![CDATA[19.63mm 2 ]]> <![CDATA[95.02mm 2 ]]> <![CDATA[T a1 +T a2 -D l12 2 / 4R l12 +D l21 2 / 4R l21 ]]> 0.49mm 0.88mm 0.61mm

[0166] The above is only a specific implementation of the embodiment of the present application, but the protection scope of the embodiment of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the embodiment of the present application, which should be included in the protection scope of the embodiment of the present application. Therefore, the protection scope of the embodiment of the present application shall be based on the protection scope of the 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 (90), a first refractive lens (10), a super lens (20) and a second refractive lens (30); the optical focal powers of the first refractive lens (10), the super lens (20) and the second refractive lens (30) are all positive; the object side surface of the first refractive lens (10) is convex toward the object side, and the image side surface of the first refractive lens (10) is convex toward the object side; any one of the first refractive lens (10) and the second refractive lens (30) is an aspherical lens, and the other of the first refractive lens (10) and the second refractive lens (30) is a spherical lens; Wherein, the infrared optical system satisfies: f l1 is the focal length of the first refractive lens (10), f l2 is the focal length of the second refractive lens (30), f is the effective focal length of the infrared optical system, and EPD is the entrance pupil diameter of the infrared optical system.

2. The infrared optical system according to claim 1, characterized in that: The first refractive lens (10) is a spherical lens; The second refractive lens (30) is an aspherical lens; the object side surface of the second refractive lens (30) is convex toward the image side; and the image side surface of the second refractive lens (30) is convex toward the image side.

3. The infrared optical system according to claim 1, characterized in that: The first refractive lens (10) is an aspherical lens; The second refractive lens (30) is a spherical lens, the object side surface of the second refractive lens (30) is convex toward the object side, and the image side surface of the second refractive lens (30) is convex toward the image side.

4. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Wherein, BFL is the optical back focal length of the infrared optical system, and 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 meets the following requirements: Among them, f m is the focal length of the superlens (20), 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 meets the following requirements: Among them, T l2 is the central thickness of the second refractive lens (30), n l2 is the material refractive index of the second refractive lens (30), c l21 is the curvature of the intersection of the object side surface of the second refractive lens (30) and the optical axis (90), c l22 is the curvature of the intersection of the image side surface of the second refractive lens (30) and the optical axis (90).

7. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Wherein, EPD is the entrance pupil diameter of the infrared optical system, F# is the aperture number of the infrared optical system, and D l1 is the effective diameter of the first refractive lens (10), D l2 is the effective diameter of the second refractive lens (30).

8. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Wherein, FOV is the maximum full field of view of the infrared optical system, R l11 is the radius of curvature of the intersection of the object side surface of the first refractive lens (10) and the optical axis (90), R l12 is the radius of curvature of the intersection of the image side surface of the first refractive lens (10) and the optical axis (90), T l1 is the central thickness of the first refractive lens (10).

9. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Among them, T a1 is the thickness of the central air gap between the first refractive lens (10) and the super lens (20) on the optical axis (90), T a2 is the thickness of the central air gap between the super lens (20) and the second refractive lens (30) on the optical axis (90), D l12 is the effective diameter of the image side of the first refractive lens (10), D l21 is the effective diameter of the object side of the second refractive lens (30), R l12 is the radius of curvature of the intersection of the image side surface of the first refractive lens (10) and the optical axis (90), R l21 is the radius of curvature of the intersection of the object side surface of the second refractive lens (30) and the optical axis (90).

10. The infrared optical system according to claim 1, characterized in that: The infrared optical system further comprises a diaphragm (40), The aperture (40) is arranged on the object side of the first refractive lens (10); Alternatively, the aperture (40) is disposed between the first refractive lens (10) and the super lens (20); Alternatively, the aperture (40) is disposed between the super lens (20) and the second refractive lens (30).

11. The infrared optical system according to claim 10, characterized in that: The aperture (40) is arranged between the first refractive lens (10) and the super lens (20).

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

Images