Large-aperture far infrared optical system and large-aperture far infrared optical lens

Abstract

The utility model discloses a large-aperture far infrared optical system and a large-aperture far infrared optical lens, the large-aperture far infrared optical system comprises a first aspheric lens, the object side surface and the image side surface of the first aspheric lens are convex to the object side; the focal power of the second aspheric lens is positive, and the object side surface and the image side surface of the second aspheric lens both protrude towards the image side; the focal power of the third aspheric lens is positive, and the object side surface and the image side surface of the third aspheric lens both protrude towards the image side; the diffractive optical element is arranged in a light path of the large-aperture far infrared optical system; wherein the first aspheric lens, the second aspheric lens and the third aspheric lens are sequentially arranged along an optical axis from an object side to an image side; the large-aperture far infrared optical system satisfies the following conditions: f2 < f3 < f1, and f1, f2 and f3 are focal lengths of the first aspherical lens, the second aspherical lens and the third aspherical lens respectively. The far infrared optical system provided by the utility model is excellent in imaging quality, large in light incoming amount, high in resolution ratio, small in size and capable of meeting the miniaturization requirement.

Description

Technical Field

[0001] This application relates to the field of optical systems, and more particularly to a large-aperture far-infrared optical system and a large-aperture far-infrared optical lens. Background Technology

[0002] The design of far-infrared optical systems typically requires matching imaging detectors. Currently, the more mature far-infrared imaging detectors on the market have resolutions of 256×192, 640×512, and 1280×1024, with pixel sizes generally around 12 micrometers. With the development of related technologies, the market demand for finer resolutions is gradually increasing, and existing 12-micrometer pixel size imaging detectors are basically unable to meet these requirements. At the same time, 8-micrometer pixel size imaging detectors have emerged on the market. Compared to 12-micrometer pixel size detectors, 8-micrometer pixel size detectors can resolve more details, but they also place higher demands on the optical system. According to the Nyquist sampling theorem, the resolution of a far-infrared optical system paired with an 8-micrometer pixel size imaging detector should reach 1000 / (8×2) = 62.5 lp / mm.

[0003] In the existing technology, some far-infrared optical systems cannot be matched with 8-micron imaging detectors, and some far-infrared optical systems also have problems such as small light intake and large size. Summary of the Invention

[0004] To address the aforementioned technical problems, this application provides a far-infrared optical system and a far-infrared optical lens, aiming to solve at least one of the above problems.

[0005] According to one aspect of the embodiments of this application, a large-aperture far-infrared optical system is disclosed, the large-aperture far-infrared optical system comprising:

[0006] The first aspherical lens has an object-side surface convex towards the object side and an image-side surface convex towards the object side.

[0007] The second aspherical lens has a positive optical power, and its object side convexes towards the image side, while its image side convexes towards the image side.

[0008] The third aspherical lens has a positive optical power, and its object side convexes towards the image side, while its image side convexes towards the image side.

[0009] A diffractive optical element is disposed in the optical path of the large-aperture far-infrared optical system;

[0010] The first aspherical lens, the second aspherical lens, and the third aspherical lens are arranged sequentially along the optical axis from the object side to the image side; the large-aperture far-infrared optical system satisfies: |f2|<|f3|<|f1|, where f1 is the focal length of the first aspherical lens, f2 is the focal length of the second aspherical lens, and f3 is the focal length of the third aspherical lens.

[0011] In some embodiments, the large aperture far-infrared optical system further includes an aperture stop, which is disposed in the optical path of the large aperture far-infrared optical system;

[0012] The large-aperture far-infrared optical system satisfies: Wherein, f is the effective focal length of the large-aperture far-infrared optical system, and D... S The aperture of the aperture stop is denoted by , the total optical length of the large aperture far-infrared optical system is denoted by TTL, and the maximum field of view of the large aperture far-infrared optical system is denoted by FOV.

[0013] In some embodiments, the large-aperture far-infrared optical system satisfies:

[0014] In some embodiments, the large-aperture far-infrared optical system satisfies: Wherein, FOV is the maximum field of view of the large aperture far-infrared optical system, and f is the effective focal length of the large aperture far-infrared optical system.

[0015] In some embodiments, the large aperture far-infrared optical system further includes an aperture stop, which is disposed in the optical path of the large aperture far-infrared optical system;

[0016] The large-aperture far-infrared optical system satisfies: Wherein, D1 is the maximum effective diameter of the first aspherical lens, D2 is the maximum effective diameter of the second aspherical lens, D3 is the maximum effective diameter of the third aspherical lens, and D... S The aperture of the aperture is denoted as .

[0017] In some embodiments, the large-aperture far-infrared optical system satisfies: Wherein, D1 is the maximum effective diameter of the first aspherical lens, D2 is the maximum effective diameter of the second aspherical lens, and D3 is the maximum effective diameter of the third aspherical lens.

[0018] In some embodiments, the large-aperture far-infrared optical system satisfies: Wherein, Imgh is half the diagonal length of the image formed by the large aperture far-infrared optical system at the maximum field of view, n1 is the refractive index of the first aspherical lens, FOV is the maximum field of view of the large aperture far-infrared optical system, FNO is the aperture number of the large aperture far-infrared optical system, and R1 is the radius of curvature of the object side surface of the first aspherical lens.

[0019] In some embodiments, the large-aperture far-infrared optical system satisfies: Wherein, the f 12 The combined focal length of the first aspherical lens and the second aspherical lens is f. 23 The combined focal length of the second aspherical lens and the third aspherical lens.

[0020] In some embodiments, the diffractive optical element is a diffractive surface, which is disposed on the object-side surface of the third aspherical lens.

[0021] A second aspect of this application provides a large-aperture far-infrared optical lens, the large-aperture far-infrared optical lens comprising: an imaging detector and a large-aperture far-infrared optical system as described in any of the preceding claims; the imaging detector is disposed on the image plane of the large-aperture far-infrared optical system.

[0022] The large-aperture far-infrared optical system provided in this application includes, along the optical axis from the object side to the image side, a first aspherical lens, a second aspherical lens, and a third aspherical lens. The object side of the first aspherical lens is convex to the object side, and the image side of the first aspherical lens is convex to the object side. The second aspherical lens has positive optical power, and both its object side and image side are convex to the image side. The third aspherical lens also has positive optical power, and both its object side and image side are convex to the image side. The large-aperture far-infrared optical system further includes a diffractive optical element, with at least one diffractive optical element disposed in the optical path of the large-aperture far-infrared optical system. The large-aperture far-infrared optical system satisfies the following condition: |f2|<|f3|<|f1|, where f1 is the focal length of the first aspherical lens, f2 is the focal length of the second aspherical lens, and f3 is the focal length of the third aspherical lens. The large-aperture far-infrared optical system provided in this application offers excellent imaging quality, a large light intake, and high resolution, making it compatible with imaging detectors with a pixel size of 8 micrometers. The large-aperture far-infrared optical system has a smaller number of lenses, ensuring a compact size and meeting miniaturization requirements. Furthermore, the large-aperture far-infrared optical system incorporates diffractive optical elements, correcting chromatic aberration while increasing the system's design flexibility. Attached Figure Description

[0023] The above and other objectives, features and advantages of this application will become more apparent from a detailed description of exemplary embodiments thereof with reference to the accompanying drawings.

[0024] Figure 1 A schematic diagram of the architecture layout of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0025] Figure 2 The diagram shows the phase distribution of the diffractive optical element of a large-aperture far-infrared optical system according to an embodiment of this application.

[0026] Figure 3 The MTF field-of-view curve of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0027] Figure 4 A dot diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0028] Figure 5 The field curve diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0029] Figure 6 The distortion diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0030] Figure 7 The diagram shows the relative illumination of a large-aperture far-infrared optical system according to an embodiment of this application.

[0031] Figure 8 A transverse chromatic aberration diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0032] Figure 9 A schematic diagram of the architecture layout of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0033] Figure 10 The diagram shows the phase distribution of the diffractive optical element of a large-aperture far-infrared optical system according to an embodiment of this application.

[0034] Figure 11 The MTF field-of-view curve of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0035] Figure 12 A dot diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0036] Figure 13 The field curve diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0037] Figure 14 The distortion diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0038] Figure 15 The diagram shows the relative illumination of a large-aperture far-infrared optical system according to an embodiment of this application.

[0039] Figure 16 A transverse chromatic aberration diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0040] Figure 17 A schematic diagram of the architecture layout of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0041] Figure 18 The diagram shows the phase distribution of the diffractive optical element of a large-aperture far-infrared optical system according to an embodiment of this application.

[0042] Figure 19 The MTF field-of-view curve of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0043] Figure 20 A dot diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0044] Figure 21 The field curve diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0045] Figure 22 The distortion diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0046] Figure 23 The diagram shows the relative illumination of a large-aperture far-infrared optical system according to an embodiment of this application.

[0047] Figure 24 A transverse chromatic aberration diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0048] Figure 25 A schematic diagram of the architecture layout of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0049] Figure 26 The diagram shows the phase distribution of the diffractive optical element of a large-aperture far-infrared optical system according to an embodiment of this application.

[0050] Figure 27 The MTF field-of-view curve of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0051] Figure 28 A dot diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0052] Figure 29The field curve diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0053] Figure 30 The distortion diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0054] Figure 31 The diagram shows the relative illumination of a large-aperture far-infrared optical system according to an embodiment of this application.

[0055] Figure 32 A transverse chromatic aberration diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0056] Figure 33 A schematic diagram of the architecture layout of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0057] Figure 34 The diagram shows the phase distribution of the diffractive optical element of a large-aperture far-infrared optical system according to an embodiment of this application.

[0058] Figure 35 The MTF field-of-view curve of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0059] Figure 36 A dot diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0060] Figure 37 The field curve diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0061] Figure 38 The distortion diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0062] Figure 39 The diagram shows the relative illumination of a large-aperture far-infrared optical system according to an embodiment of this application.

[0063] Figure 40 A transverse chromatic aberration diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0064] Figure 41 A schematic diagram of the architecture layout of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0065] Figure 42 The diagram shows the phase distribution of the diffractive optical element of a large-aperture far-infrared optical system according to an embodiment of this application.

[0066] Figure 43 The MTF field-of-view curve of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0067] Figure 44 A dot diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0068] Figure 45 The field curve diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0069] Figure 46 The distortion diagram of a large-aperture far-infrared optical system in one embodiment of this application is shown.

[0070] Figure 47 The diagram shows the relative illumination of a large-aperture far-infrared optical system according to an embodiment of this application.

[0071] Figure 48 A transverse chromatic aberration diagram of a large-aperture far-infrared optical system according to an embodiment of this application is shown.

[0072] Figure Labels

[0073] 100. Large aperture far-infrared optical system;

[0074] 10. First aspherical lens;

[0075] 20. Second aspherical lens;

[0076] 30. Third aspherical lens;

[0077] 40. Diffractive optical elements;

[0078] 50. Aperture;

[0079] 60. Protective glass;

[0080] 70. Object surface;

[0081] 80. Like a face;

[0082] 90. Optical axis. Detailed Implementation

[0083] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided to make the description of this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The drawings are merely illustrative of this application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted.

[0084] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more exemplary embodiments. Numerous specific details are provided in the following description to give a full understanding of exemplary embodiments of this application. However, those skilled in the art will recognize that the technical solutions of this application can be practiced with one or more specific details omitted, or other modules, components, etc., can be employed. In other instances, well-known structures, methods, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of this application.

[0085] Please see Figure 1 , Figure 1 The diagram shows a schematic layout of a large-aperture far-infrared optical system in one embodiment of this application, wherein the optical axis is the center line of the light beam, and the direction along the optical axis from the object plane to the image plane is consistent with the direction along the optical axis from the object side to the image side.

[0086] The large-aperture far-infrared optical system 100 includes a first aspherical lens 10, a second aspherical lens 20, a third aspherical lens 30, and a diffractive optical element 40. The first aspherical lens 10, the second aspherical lens 20, and the third aspherical lens 30 are arranged sequentially along the optical axis 90 from the object plane 70 to the image plane 80. The diffractive optical element 40 is disposed in the optical path of the large-aperture far-infrared optical system 100, for example, between any two adjacent lenses, or on the surface of any one or more lenses.

[0087] The object-side surface of the first aspherical lens 10 convexes towards the object side, and the image-side surface of the first aspherical lens 10 convexes towards the object side. The optical power of the first aspherical lens 10 can be positive or negative. Specifically, in some embodiments, the optical power of the first aspherical lens 10 is positive; in some embodiments, the optical power of the first aspherical lens 10 is negative.

[0088] The second aspherical lens 20 has a positive optical power, and the object side of the second aspherical lens 20 is convex to the image side, while the image side of the second aspherical lens 20 is convex to the image side.

[0089] The third aspherical lens 30 has a positive optical power, and the object side of the third aspherical lens 30 is convex to the image side, while the image side of the third aspherical lens 30 is convex to the image side.

[0090] At least one diffractive optical element 40 is provided. At least one diffractive optical element 40 is provided in the optical path of the large aperture far-infrared optical system 100. The diffractive optical element 40 has negative dispersion. When used in combination with conventional refractive lenses (first aspherical lens 10, second aspherical lens 20, and third aspherical lens 30), it can effectively correct the chromatic aberration of the large aperture far-infrared optical system 100.

[0091] The large-aperture far-infrared optical system 100 satisfies condition one: |f2|<|f3|<|f1|, where f1 is the focal length of the first aspherical lens 10, f2 is the focal length of the second aspherical lens 20, and f3 is the focal length of the third aspherical lens 30. f1, f2, and f3 have the same dimension, all being units of length, such as millimeters.

[0092] By using conditional formula one, the optical power of the large-aperture far-infrared optical system 100 can be reasonably allocated, ensuring that the large-aperture far-infrared optical system 100 has low tolerance sensitivity while having excellent imaging quality.

[0093] The large-aperture far-infrared optical system 100 provided in this application has excellent imaging quality, a large light intake, and high resolution, making it compatible with imaging detectors with a pixel size of 8 micrometers. The large-aperture far-infrared optical system 100 has a small number of lenses, ensuring a compact size and meeting miniaturization requirements. Furthermore, the large-aperture far-infrared optical system 100 incorporates diffractive optical elements 40, which correct chromatic aberration while increasing the system's design flexibility.

[0094] In some embodiments, the large-aperture far-infrared optical system 100 includes only one diffractive optical element 40, and the position of the diffractive optical element 40 can be any of the following:

[0095] A: The diffractive optical element 40 is disposed on the object side of any lens;

[0096] B: The diffractive optical element 40 is disposed on the image side of any lens;

[0097] C: Diffractive optical element 40 is disposed between any two adjacent lenses;

[0098] D: The diffractive optical element 40 is disposed on the object side of the first aspherical lens 10;

[0099] E: The diffractive optical element 40 is disposed on the image side of the third aspherical lens 30.

[0100] In some embodiments, when the large-aperture far-infrared optical system 100 includes at least two diffractive optical elements 40, the positions of each diffractive optical element are combinations of the above-described cases A, B, C, D, and E. For example, when the large-aperture far-infrared optical system 100 includes two diffractive optical elements 40, the positions of the two diffractive optical elements 40 can be any combination of two from A, B, C, D, and E. When the large-aperture far-infrared optical system 100 includes three diffractive optical elements 40, the positions of the three diffractive optical elements 40 can be any combination of three from A, B, C, D, and E.

[0101] Regarding the aforementioned diffractive optical element 40, when it is disposed on the surface of a lens, it can be implemented using a diffractive surface. A diffractive surface is a special optical surface that introduces minute periodic or aperiodic structures to cause diffraction of incident light, thereby achieving precise control over the shape, direction, and intensity distribution of the light beam. When the diffractive optical element 40 is disposed between any two adjacent lenses, or when it is disposed on the object side of the first aspherical lens 10, or when it is disposed on the image side of the third aspherical lens 30, it can be a superlens or a diffractive surface integrated onto a flat glass plate.

[0102] In some embodiments, the diffractive optical element 40 is a diffractive surface. The object-side surface of the first aspherical lens 10, the image-side surface of the first aspherical lens 10, the object-side surface of the second aspherical lens 20, the image-side surface of the second aspherical lens 20, the object-side surface of the third aspherical lens 30, and the image-side surface of the third aspherical lens 30 are all target surfaces on which the diffractive optical element 40 can be disposed. At least one target surface is provided with a diffractive surface. The diffractive surface has the advantages of high diffraction efficiency and good dispersion. Introducing a diffractive surface in the large aperture far-infrared optical system 100 can improve the degree of design freedom.

[0103] Furthermore, in some embodiments, the diffractive optical element 40 is a diffractive surface, which is disposed on the object-side surface of the third aspherical lens 30. Compared to placing the diffractive surface in other positions, the large-aperture far-infrared optical system 100 exhibits superior imaging quality when the diffractive surface is disposed on the object-side surface of the third aspherical lens 30. Compared to the large-aperture far-infrared optical system 100 having multiple diffractive surfaces, the large-aperture far-infrared optical system 100 exhibits higher transmittance when it has only one diffractive surface, and this diffractive surface is disposed on the object-side surface of the third aspherical lens 30.

[0104] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition two: Where f1 is the focal length of the first aspherical lens 10, f2 is the focal length of the second aspherical lens 20, and f3 is the focal length of the third aspherical lens 30. f1, f2, and f3 have the same dimension, all being units of length, such as millimeters.

[0105] Equation 2 indicates the power distribution relationship of the large-aperture far-infrared optical system 100. Satisfying Equation 2 is beneficial for the aberration correction of the large-aperture far-infrared optical system 100, resulting in excellent image quality and facilitating aberration balance. Furthermore, satisfying Equation 2 reduces the sensitivity of the large-aperture far-infrared optical system 100 to assembly tolerances, thereby improving the assembly yield of the corresponding lens.

[0106] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition three: Here, FOV (Field of View) is the maximum field of view of the large-aperture far-infrared optical system 100, and the unit of FOV is degrees. f is the effective focal length of the large-aperture far-infrared optical system 100, and the dimension of f is a unit of length, such as millimeters.

[0107] Condition 5 ensures that the imaging clarity of the large-aperture far-infrared optical system 100 meets the requirements of an imaging detector with a pixel size of 8 micrometers. At the same time, Condition 5 also ensures that the large-aperture far-infrared optical system 100 can collect a larger field of view information, thereby improving the efficiency of information reception of the large-aperture far-infrared optical system 100.

[0108] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition four: Wherein, D1 is the maximum effective diameter of the first aspherical lens 10, D2 is the maximum effective diameter of the second aspherical lens 20, and D3 is the maximum effective diameter of the third aspherical lens 30. In this application, the maximum effective diameter of a lens is the larger of the maximum effective diameter of the object-side surface and the maximum effective diameter of the image-side surface of the corresponding lens. For example, the maximum effective diameter D1 of the first aspherical lens 10 is the larger of the maximum effective diameter of the object-side surface and the maximum effective diameter of the image-side surface of the first aspherical lens 10. The maximum effective diameter of the object-side surface of a lens refers to the diameter of the maximum light-transmitting area of ​​the object-side surface of the lens, and the same applies to the maximum effective diameter of the image-side surface. f1 is the focal length of the first aspherical lens 10, f2 is the focal length of the second aspherical lens 20, and f3 is the focal length of the third aspherical lens 30. D1, D2, D3, f1, f2, and f3 have the same dimension, all being units of length, such as millimeters.

[0109] Condition four ensures a smoother light propagation path in the large-aperture far-infrared optical system 100, reduces the overall tolerance sensitivity of the large-aperture far-infrared optical system 100, and improves the assembly yield of the large-aperture far-infrared optical system 100. Furthermore, condition four ensures the imaging performance of the large-aperture far-infrared optical system 100.

[0110] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition five: Where Imgh is half the diagonal length of the image formed by the large-aperture far-infrared optical system 100 at its maximum field of view. n1 is the refractive index of the first aspherical lens 10; in this application, n1 is the refractive index at a wavelength of 10.6 micrometers. FOV is the maximum field of view of the large-aperture far-infrared optical system 100, and the unit of FOV is angle, such as degrees. FNO is the aperture number of the large-aperture far-infrared optical system 100, i.e., FNO is the F-number of the large-aperture far-infrared optical system 100. R1 is the radius of curvature of the object-side surface of the first aspherical lens 10. Imgh and R1 have the same dimension, both being units of length, such as millimeters.

[0111] Condition 5 indicates the range of system parameters required for the large-aperture far-infrared optical system 100 to achieve excellent imaging quality when paired with an imaging detector with a pixel size of 8 micrometers. It is worth noting that the pixel size of the imaging detector adapted to the large-aperture far-infrared optical system 100 includes, but is not limited to, 8 micrometers, and the number of pixels of the imaging detector adapted to the large-aperture far-infrared optical system 100 includes, but is not limited to, 640*512.

[0112] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition six: Among them, f 12 f is the combined focal length of the first aspherical lens 10 and the second aspherical lens 20. 23 f is the combined focal length of the second aspherical lens 20 and the third aspherical lens 30. 12 f 23 They have the same dimensions, both being units of length, such as millimeters.

[0113] Condition 6 is beneficial for aberration correction in the large-aperture far-infrared optical system 100, ensuring that the large-aperture far-infrared optical system 100 has excellent imaging quality.

[0114] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition seven: Wherein, TTL (Total Track Length) is the total optical length of the large-aperture far-infrared optical system 100, and f is the effective focal length of the large-aperture far-infrared optical system 100. TTL and f have the same dimension, both being units of length, such as millimeters.

[0115] Condition 7 ensures that the large-aperture far-infrared optical system 100 has a small total optical length, which in turn ensures that the large-aperture far-infrared optical system 100 has a small volume, giving the large-aperture far-infrared optical system 100 the advantage of miniaturization.

[0116] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition eight: Wherein, BFL (Back focal length) is the optical back focal length of the large-aperture far-infrared optical system 100, and f is the effective focal length of the large-aperture far-infrared optical system 100. BFL and f have the same dimension, both being units of length, such as millimeters.

[0117] If the optical back focal length is too large, the overall optical length will be too large, resulting in an excessively large size for the large-aperture far-infrared optical system 100. Conversely, if the optical back focal length is too small, the space between the third aspherical lens 30 and the image plane 80 will be too small, which is detrimental to the installation of components such as the shutter. Condition three ensures that the large-aperture far-infrared optical system 100 has a suitable optical back focal length, allowing it to maintain a small size while also having a suitable optical back focal length. This provides sufficient space for installing components such as the shutter, preventing collisions between components.

[0118] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition nine: Wherein, D1 is the maximum effective diameter of the first aspherical lens 10, and D3 is the maximum effective diameter of the third aspherical lens 30. D1 and D3 have the same dimension, both being units of length, such as millimeters.

[0119] The lower limit of condition nine ensures that the large-aperture far-infrared optical system 100 has a small volume, thereby ensuring that the aperture of the large-aperture far-infrared optical system 100 is not too large. The lower limit of condition nine also ensures that the large-aperture far-infrared optical system 100 has sufficient relative illumination.

[0120] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition ten: Among them, R 31 Let SAG be the radius of curvature of the object-side surface of the third aspherical lens 30. 31 The sag of the object side surface of the third aspherical lens 30 at its maximum effective radius. In this application, the sag at the maximum effective radius is the sag on the corresponding surface whose distance from the center of the corresponding surface on the optical axis 90 is equal to the effective radius of that surface, i.e., SAG. 31 R is the height of the object-side surface of the third aspherical lens 30, located at a distance on the optical axis 90 equal to the effective radius of the object-side surface of the third aspherical lens 30 from the center of the object-side surface. 32 SAG is the radius of curvature of the image-side surface of the third aspherical lens 30. 32 The sag of the image-side surface of the third aspherical lens 30 at its maximum effective radius is called SAG. 31R is the height of the image-side surface of the third aspherical lens 30, located at a distance on the optical axis 90 equal to the effective radius of the image-side surface of the third aspherical lens 30 from the center of the image-side surface. 31 SAG 31 R 32 SAG 32 They have the same dimensions, both being units of length, such as millimeters.

[0121] Condition six can effectively control the spherical aberration and off-axis coma of the large aperture far-infrared optical system 100. At the same time, condition five can also control the surface shape of the third aspherical lens 30, making the surface shape of the third aspherical lens 30 more reasonable and easier to process.

[0122] In some embodiments, the large-aperture far-infrared optical system 100 satisfies condition eleven: Where ∑CT equals the sum of the center thicknesses of the first aspherical lens 10, the second aspherical lens 20, and the third aspherical lens 30, and BFL is the optical back focal length of the large-aperture far-infrared optical system 100. 13 ∑CT, BFL, C is the distance on the optical axis 90 between the object-side surface of the first aspherical lens 10 and the image-side surface of the third aspherical lens 30. TTL is the total optical length of the large-aperture far-infrared optical system 100. 13 Both TTL and TTL have the same dimension, both being units of length, such as millimeters.

[0123] The upper limit of condition eleven constrains the thickness of the first aspherical lens 10, the second aspherical lens 20, and the third aspherical lens 30 to reduce the amount of lens material used, thereby lowering the cost of the large-aperture far-infrared optical system 100. The lower limit of condition eleven ensures that the large-aperture far-infrared optical system 100 has a small overall optical length, thus ensuring that the large-aperture far-infrared optical system 100 has a small volume.

[0124] The large aperture far-infrared optical system 100 also includes an aperture stop 50, which is used to control the amount of light entering the large aperture far-infrared optical system 100, ensuring that the large aperture far-infrared optical system 100 can work effectively and generate high-quality images.

[0125] In some embodiments, the aperture stop 50 is disposed on the object side of the first aspherical lens 10. Specifically, the position of the aperture stop 50 satisfies any of the following conditions:

[0126] (1) The aperture 50 is disposed on the object side of the first aspherical lens 10, and the aperture 50 is disposed at a distance from the first aspherical lens 10.

[0127] (2) The aperture 50 is disposed on the object side of the first aspherical lens 10, and the aperture 50 is disposed on the object side of the first aspherical lens 10.

[0128] In some embodiments, the aperture stop 50 is disposed between any two adjacent lenses. Specifically, the position of the aperture stop 50 satisfies any of the following conditions:

[0129] (1) The aperture 50 is located between the first aspherical lens 10 and the second aspherical lens 20, and the aperture 50 is disposed on the image side of the first aspherical lens 10.

[0130] (2) The aperture 50 is located between the first aspherical lens 10 and the second aspherical lens 20, and the aperture 50 is spaced apart from both the first aspherical lens 10 and the second aspherical lens 20.

[0131] (3) The aperture 50 is located between the first aspherical lens 10 and the second aspherical lens 20, and the aperture 50 is disposed on the object side of the second aspherical lens 20.

[0132] (4) The aperture 50 is located between the second aspherical lens 20 and the third aspherical lens 30, and the aperture 50 is disposed on the image side of the second aspherical lens 20.

[0133] (5) The aperture 50 is located between the second aspherical lens 20 and the third aspherical lens 30, and the aperture 50 is spaced apart from both the second aspherical lens 20 and the third aspherical lens 30.

[0134] (6) The aperture 50 is located between the second aspherical lens 20 and the third aspherical lens 30, and the aperture 50 is disposed on the object side of the third aspherical lens 30.

[0135] Furthermore, in some embodiments, the aperture stop 50 is located between the first aspherical lens 10 and the second aspherical lens 20. Compared to setting the aperture stop 50 in other positions, when the aperture stop 50 is set between the first aspherical lens 10 and the second aspherical lens 20, the large aperture far-infrared optical system 100 has better imaging quality.

[0136] In some embodiments, the aperture stop 50 is disposed in the optical path of the large-aperture far-infrared optical system 100, and the large-aperture far-infrared optical system 100 satisfies condition twelve: Where f is the effective focal length of the large-aperture far-infrared optical system 100, and D S f represents the aperture of 50mm, and TTL represents the total optical length of the large-aperture far-infrared optical system 100. S Both TTL and FOV have the same dimensions, both being units of length, such as millimeters. FOV is the maximum field of view of a large-aperture far-infrared optical system, and its unit is degrees.

[0137] The lower limit of Conditional Equation Twelve ensures that the large-aperture far-infrared optical system 100 has sufficient light intake, improving light energy utilization and allowing for the acquisition of more details of the photographed object. The upper limit of Conditional Equation Twelve ensures that the large-aperture far-infrared optical system 100 has a small size, meeting the requirements for miniaturization.

[0138] In some embodiments, the aperture stop 50 is disposed in the optical path of the large-aperture far-infrared optical system 100, and the large-aperture far-infrared optical system 100 satisfies condition thirteen: Wherein, D1 is the maximum effective diameter of the first aspherical lens 10, D2 is the maximum effective diameter of the second aspherical lens 20, and D3 is the maximum effective diameter of the third aspherical lens 30. S This refers to an aperture of 50mm. D1, D2, D3, D S They have the same dimensions, both being units of length, such as millimeters.

[0139] The upper limit of conditional equation thirteen controls the overall aperture of the large-aperture far-infrared optical system 100, which is beneficial for its miniaturization. Furthermore, when the large-aperture far-infrared optical system 100 has a reasonable aperture, the apertures of the first aspherical lens 10, the second aspherical lens 20, and the third aspherical lens 30 will not be too large, reducing the material usage of these lenses and thus lowering the cost of the large-aperture far-infrared optical system 100. The lower limit of conditional equation thirteen prevents excessively low relative illumination in the large-aperture far-infrared optical system 100; that is, the lower limit of conditional equation thirteen ensures the relative illumination threshold of the far-infrared optical system.

[0140] In some embodiments, the large-aperture far-infrared optical system 100 further includes a protective glass 60 located on the image side of the third aspherical lens 30. The protective glass 60 is used to protect the imaging detector disposed on the image plane 80 to reduce the probability of damage to the imaging detector.

[0141] The large-aperture far-infrared optical system 100 provided in this application has the following advantages:

[0142] (1) Effective focal length meets: 6.1 mm ± 5%

[0143] (2) F number: 0.9~1.0;

[0144] (3) The absolute value of distortion is ≤12%;

[0145] (4) Relative illumination > 70%;

[0146] (5) Total optical length (TTL) < 14 mm;

[0147] (6) Back focal length (BFL) > 5.05 mm;

[0148] (7) It can be adapted to imaging detectors with a pixel size of 8 micrometers;

[0149] This application provides six large-aperture far-infrared optical systems 100 that meet usage requirements in six exemplary embodiments. The large-aperture far-infrared optical systems 100 provided in each embodiment of this application will be described in detail below.

[0150] Example 1

[0151] Figure 1 This diagram illustrates the architectural layout of the large-aperture far-infrared optical system 100 provided in Embodiment 1. Figure 1 The large-aperture far-infrared optical system 100, along the optical axis 90 from the object plane 70 to the image plane 80, includes, in sequence: a first aspherical lens 10, an aperture 50, a second aspherical lens 20, a diffractive optical element 40, a third aspherical lens 30, and a protective glass 60. The diffractive optical element 40 is a diffractive surface, which is disposed on the object-side surface of the third aspherical lens 30. Some parameters of the large-aperture far-infrared optical system 100 provided in Embodiment 1 are shown in Table 1-1.

[0152] Table 1-1. Partial parameters of the large-aperture far-infrared optical system 100 provided in Example 1

[0153] Optical indicators data Effective focal length 6.104mm F number 0.9 distortion -11.64％ Relative Illuminance >74.8％ Total optical length (TTL) 13.056mm Optical Back Focus (BFL) 5.433mm Maximum field of view (FOV) (2ω) 62.994° Operating band 8μm-12μm

[0154] As shown in Table 1-1, the total optical length of the large-aperture far-infrared optical system 100 is relatively short, only 13.06 mm. Therefore, the large-aperture far-infrared optical system 100 provided in Example 1 has a relatively small volume. The large-aperture far-infrared optical system 100 has an F-number of 0.9, which allows for a large amount of light to enter, thereby ensuring excellent imaging quality.

[0155] Along the optical axis 90 from the object plane 70 to the image plane 80, starting from the object plane 70, each surface in the large aperture far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain Table 1-2 below.

[0156] Table 1-2. Parameters of various surfaces in the large-aperture far-infrared optical system 100 provided in Example 1

[0157] Surface number Surface type Radius of curvature (mm) Thickness (mm) Material 0 flat unlimited unlimited - 1 even aspherical surface 4.242 0.900 Chalcogenide Glass 2 even aspherical surface 3.665 1.416 - 3 Aperture unlimited 0.419 - 4 even aspherical surface -50.483 2.000 Chalcogenide Glass 5 even aspherical surface -9.693 0.670 - 6 even aspherical surface -8.076 2.218 Chalcogenide Glass 7 even aspherical surface -7.195 4.708 - 8 flat unlimited 0.625 silicon 9 flat unlimited 0.100 - 10 flat unlimited - -

[0158] For each surface in Table 1-2, surface 0 is the object plane 70, surface 1 is the object-side surface of the first aspherical lens 10, and surface 2 is the image-side surface of the first aspherical lens 10. Surface 3 is the aperture stop 50. Surface 4 is the object-side surface of the second aspherical lens 20, and surface 5 is the image-side surface of the second aspherical lens 20. Surface 6 is the object-side surface of the third aspherical lens 30, and surface 7 is the image-side surface of the third aspherical lens 30 with a diffraction surface located on it. Surface 8 is the object-side surface of the protective glass 60, surface 9 is the image-side surface of the protective glass 60, and surface 10 is the image plane 80.

[0159] As shown in Table 1-2, surface 1 is an even-order aspherical surface with a radius of curvature of 4.242 mm. The distance between surface 1 and surface 2 is 0.900 mm, and the material between them is chalcogenide glass. Surface 2 is an even-order aspherical surface with a radius of curvature of 3.665 mm. The distance between surface 2 and surface 3 is 1.416 mm, and the material between them is air. Surface 3 is a plane with an infinite radius of curvature. The distance between surface 3 and surface 4 is 0.419 mm, and the material between them is air. Surface 4 is an even-order aspherical surface with a radius of curvature of -50.483 mm. The distance between surface 4 and surface 5 is 2.000 mm, and the material between them is chalcogenide glass. Surface 5 is an even-order aspherical surface with a radius of curvature of -9.693 mm. The distance between surface 5 and surface 6 is 0.670 mm, and the material between them is air. Surface 6 is an even-order aspherical surface with a radius of curvature of -8.076 mm. The distance between surface 6 and surface 7 is 2.218 mm, and the material between them is chalcogenide glass. Surface 7 is an even-order aspherical surface with a radius of curvature of -7.195 mm. The distance between surface 7 and surface 8 is 4.708 mm, and the material between them is air. Surface 8 is a plane with an infinite radius of curvature. The distance between surface 8 and surface 9 is 0.625 mm, and the material between them is silicon. Surface 9 is a plane with an infinite radius of curvature. The distance between surface 9 and surface 10 is 0.100 mm, and the material between them is air.

[0160] Surfaces 1, 2, 4, 5, 6, and 7 are all even-order aspherical surfaces, and their surface shapes satisfy the following relationship:

[0161]

[0162] Where Z(r) is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis 90°; c is the surface curvature of the aspherical surface, c = 1 / R, where R is the radius of curvature of the aspherical surface; k is the conic coefficient; A, B, C, D... are aspherical coefficients. The values ​​of k, A, B, C, D... for surfaces 1, 2, 4, 5, 6, and 7 can be found in Table 1-3.

[0163] Table 1-3. Coefficients of even-order aspherical surfaces in the large-aperture far-infrared optical system 100 provided in Example 1

[0164] surface k A B C D E 1 -5.36E-02 5.88E-04 -2.00E-04 3.42E-06 -1.10E-06 2.30E-09 2 -3.39E-01 1.58E-03 -7.26E-05 -4.78E-05 1.30E-06 -5.13E-08 4 -9.90E+01 -1.26E-03 3.96E-05 -2.93E-05 3.30E-06 -1.98E-07 5 -1.36E+00 6.82E-05 -1.24E-04 2.36E-06 7.79E-08 -1.05E-08 6 2.36E+00 1.81E-03 -1.79E-04 7.25E-06 -5.48E-08 1.02E-08 7 -6.72E+00 -1.65E-03 1.85E-05 -1.31E-06 5.96E-08 -1.67E-09

[0165] Please refer to Table 1-3. For surface 1, k is -5.36E-02, A is 5.88E-04, B is -2.00E-04, C is 3.42E-06, D is -1.10E-06, and E is 2.30E-09. The coefficients of even-order aspherical surfaces 2, 4, 5, 6, and 7 are not described here.

[0166] The diffraction plane is located on surface 6, and the phase expression of the diffraction plane is: Where ρ = r / r0, r is the radius of the diffraction surface, r0 is the normalized radius of the diffraction surface, and A i Here, represents the phase coefficient of the diffraction surface, and N is the number of terms in the polynomial. The coefficients of the diffraction surface can be found in Table 1-4.

[0167] Table 1-4. Coefficients of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Example 1

[0168] surface face shape Normalized radius A1 A2 A3 A4 6 Binary Diffraction Surface 3.6mm -1.07E+01 -5.93E+00 -6.47E+01 3.05E+02

[0169] Please see Figure 2 , Figure 2 The phase distribution diagram of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Embodiment 1 is shown. Figure 2 The horizontal axis represents the distance from the center of the diffraction plane. Figure 2 The vertical axis represents the phase. Since the phase is a periodic function of 2π, there exists a relationship... (where n is an integer), therefore Figure 2 The phase of the diffraction surface in Example 1 is normalized by taking the remainder of 2π to meet the actual processing requirements of the diffraction surface.

[0170] Please see Figure 3 , Figure 3 The MTF (Modulation Transfer Function) field-of-view curve of the large-aperture far-infrared optical system 100 provided in Embodiment 1 is shown. Figure 3 The horizontal axis represents the image height, meaning the horizontal axis measures the field of view using the image height, and the unit of the horizontal axis is millimeters. Figure 3 The vertical axis represents the MTF value. Figure 3 The table lists the sagittal curve S1 and meridional curve T1 for the MTF at a spatial frequency of 10 lp / mm as a function of field of view; the sagittal curve S2 and meridional curve T2 for the MTF at a spatial frequency of 21 lp / mm as a function of field of view; the sagittal curve S3 and meridional curve T3 for the MTF at a spatial frequency of 42 lp / mm as a function of field of view; and the sagittal curve S4 and meridional curve T4 for the MTF at a spatial frequency of 62.5 lp / mm as a function of field of view. Figure 3 It can be seen that at a spatial frequency of 62.5 lp / mm, the MTF is greater than 0.17 across the entire field of view, indicating that the large-aperture far-infrared optical system 100 has excellent imaging quality.

[0171] Please see Figure 4 , Figure 4 A dot plot of the large-aperture far-infrared optical system 100 provided in Embodiment 1 is shown. Figure 4 As can be seen, the maximum number of dots in the full field of view is less than 2 pixels (16 micrometers). Therefore, the light converges and is concentrated, and the large aperture far-infrared optical system 100 provided in Example 1 has a sharp imaging effect.

[0172] Please see Figure 5 , Figure 5 The field curvature diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 1 is shown. Figure 5 The horizontal axis represents the field curvature, and its unit is millimeters; Figure 5 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 5 In the diagram, S1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the sagittal direction, and T1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the meridional direction; S2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the sagittal direction, and T2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the meridional direction; S3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the sagittal direction, and T3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the meridional direction. Figure 5 It can be seen that the field curvature of the large-aperture far-infrared optical system 100 in the sagittal direction is 0.1447 mm, and the field curvature of the large-aperture far-infrared optical system 100 in the meridional direction is 0.1309 mm, which meets the field curvature requirements of the excellent imaging quality standard.

[0173] Please see Figure 6 , Figure 6 The distortion diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 1 is shown. Figure 6 The horizontal axis represents distortion, and its unit is percentage; Figure 6 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 6The distortion curves of the large-aperture far-infrared optical system 100 provided in Example 1 at wavelengths of 8 micrometers, 10 micrometers, and 12 micrometers are shown respectively. Since the three curves almost completely overlap, this embodiment does not distinguish between the three curves. Figure 6 It can be seen that the maximum distortion of the large aperture far-infrared optical system 100 provided in Example 1 is -11.64%, which meets the requirements for clear imaging.

[0174] Please see Figure 7 , Figure 7 The relative illumination diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 1 is shown. Figure 7 The horizontal axis represents the image height, and its unit is millimeters. Figure 7 The vertical axis represents relative illumination. (From...) Figure 7 It can be seen that the relative illuminance of the large aperture far-infrared optical system 100 provided in Example 1 is greater than 74% within the entire field of view, and the brightness of the image is relatively uniform.

[0175] Please see Figure 8 , Figure 8 The diagram shows the transverse chromatic aberration of the large-aperture far-infrared optical system 100 provided in Example 1 under far-infrared light with wavelengths of 8 micrometers, 10 micrometers, and 12 micrometers. Figure 8 The x-axis represents the position of light rays of different wavelengths on the perpendicular image plane 80, in micrometers; Figure 8 The vertical axis represents the image height, and its unit is millimeters. Figure 8 The CCP presented three curves. The curve at 0 micrometers represents far-infrared light with a wavelength of 10 micrometers. Because the other two curves are too close together, they are not distinguished. Figure 8 It is known that the maximum transverse chromatic aberration is less than 2 micrometers across the entire field of view. Therefore, the large-aperture far-infrared optical system 100 provided in Example 1 has good chromatic aberration correction capability.

[0176] Example 2

[0177] Figure 9 This diagram illustrates the architectural layout of the large-aperture far-infrared optical system 100 provided in Embodiment 2. Figure 9 The large-aperture far-infrared optical system 100, along the optical axis 90 from the object plane 70 to the image plane 80, includes, in sequence: a first aspherical lens 10, an aperture 50, a second aspherical lens 20, a diffractive optical element 40, a third aspherical lens 30, and a protective glass 60. The diffractive optical element 40 is a diffraction surface, which is located on the object-side surface of the third aspherical lens 30. Some parameters of the large-aperture far-infrared optical system 100 provided in Example 2 are shown in Table 2-1.

[0178] Table 2-1. Partial parameters of the large-aperture far-infrared optical system 100 provided in Example 2

[0179] Optical indicators data Effective focal length 6.151mm F number 0.9 distortion -11.24％ Relative Illuminance >74％ Total optical length (TTL) 13.562mm Optical Back Focus (BFL) 5.259mm Maximum field of view (FOV) (2ω) 61.968° Operating band 8μm-12μm

[0180] As shown in Table 2-1, the total optical length of the large-aperture far-infrared optical system 100 is relatively short, only 13.56 mm. Therefore, the large-aperture far-infrared optical system 100 provided in Example 2 has a relatively small volume. The large-aperture far-infrared optical system 100 has an F-number of 0.9, which allows for a large amount of light to enter, thus ensuring excellent imaging quality.

[0181] Along the optical axis 90 from the object plane 70 to the image plane 80, starting from the object plane 70, each surface in the large aperture far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain Table 2-2 below.

[0182] Table 2-2. Parameters of various surfaces in the large-aperture far-infrared optical system 100 provided in Example 2

[0183]

[0184]

[0185] For the analysis of each surface in Table 2-2, please refer to Example 1. This example will not analyze each surface again.

[0186] Surfaces 1, 2, 4, 5, 6, and 7 are all even-order aspherical surfaces, and their surface shapes satisfy the following relationship:

[0187]

[0188] Where Z(r) is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis 90°; c is the surface curvature of the aspherical surface, c = 1 / R, where R is the radius of curvature of the aspherical surface; k is the conic coefficient; A, B, C, D... are aspherical coefficients. The values ​​of k, A, B, C, D... for surfaces 1, 2, 4, 5, 6, and 7 can be found in Table 2-3.

[0189] Table 2-3. Coefficients of even-order aspherical surfaces in the large-aperture far-infrared optical system 100 provided in Example 2

[0190] surface k A B C D E 1 8.99E-01 -9.03E-04 -6.30E-05 -5.51E-08 -3.57E-07 2.38E-08 2 -4.04E-01 1.88E-04 -1.01E-05 -1.77E-05 2.92E-06 -2.20E-07 4 -9.90E+01 -1.63E-03 -1.05E-06 -2.05E-05 2.72E-06 -2.02E-07 5 8.67E-02 -1.23E-03 -4.16E-05 1.46E-06 9.92E-08 -3.40E-08 6 2.71E+00 1.33E-04 -5.78E-05 8.65E-06 -7.31E-07 7.23E-09 7 -4.04E+00 -1.61E-03 2.67E-05 -2.01E-06 6.02E-08 -1.92E-09

[0191] The coefficients of each even-order aspheric surface of surfaces 1, 2, 4, 5, 6 and 7 can be found in Table 2-3. In this embodiment, the specific values ​​of each even-order aspheric surface coefficient will not be described in detail.

[0192] The diffraction plane is located on surface 6, and the phase expression of the diffraction plane is: Where ρ = r / r0, r is the radius of the diffraction surface, r0 is the normalized radius of the diffraction surface, and A i Here, represents the phase coefficient of the diffraction surface, and N is the number of terms in the polynomial. The coefficients of the diffraction surface can be found in Table 2-4.

[0193] Table 2-4. Coefficients of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Example 2

[0194]

[0195]

[0196] Please see Figure 10 , Figure 10 The phase distribution diagram of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Embodiment 2 is shown. Figure 10 The horizontal axis represents the distance from the center of the diffraction plane. Figure 10 The vertical axis represents the phase. Since the phase is a periodic function of 2π, there exists a relationship... (where n is an integer), therefore Figure 10 The phase of the diffraction surface in Example 2 is normalized by taking the remainder of 2π to meet the actual processing requirements of the diffraction surface.

[0197] Please see Figure 11 , Figure 11 The MTF field-of-view curve of the large-aperture far-infrared optical system 100 provided in Embodiment 2 is shown. Figure 11 The horizontal axis represents the image height, meaning the horizontal axis measures the field of view using the image height, and the unit of the horizontal axis is millimeters. Figure 11 The vertical axis represents the MTF value. Figure 11 The table lists the sagittal curve S1 and meridional curve T1 for the MTF at a spatial frequency of 10 lp / mm as a function of field of view; the sagittal curve S2 and meridional curve T2 for the MTF at a spatial frequency of 21 lp / mm as a function of field of view; the sagittal curve S3 and meridional curve T3 for the MTF at a spatial frequency of 42 lp / mm as a function of field of view; and the sagittal curve S4 and meridional curve T4 for the MTF at a spatial frequency of 62.5 lp / mm as a function of field of view. Figure 11 It can be seen that at a spatial frequency of 62.5 lp / mm, the MTF is greater than 0.17 across the entire field of view, indicating that the large-aperture far-infrared optical system 100 has excellent imaging quality.

[0198] Please see Figure 12 , Figure 12 A dot plot of the large-aperture far-infrared optical system 100 provided in Embodiment 2 is shown, consisting of... Figure 12 As can be seen, the maximum number of dots in the full field of view is less than 2 pixels (16 micrometers). Therefore, the light converges and is concentrated, and the large aperture far-infrared optical system 100 provided in Example 2 has a sharp imaging effect.

[0199] Please see Figure 13 , Figure 13 The field curvature diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 2 is shown. Figure 13 The horizontal axis represents the field curvature, and its unit is millimeters; Figure 13 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 13 In the diagram, S1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the sagittal direction, and T1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the meridional direction; S2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the sagittal direction, and T2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the meridional direction; S3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the sagittal direction, and T3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the meridional direction. Figure 13 It can be seen that the field curvature of the large-aperture far-infrared optical system 100 in the sagittal direction is 0.0447 mm, and the field curvature of the large-aperture far-infrared optical system 100 in the meridional direction is 0.0510 mm, which meets the field curvature requirements of the excellent imaging quality standard.

[0200] Please see Figure 14 , Figure 14 The distortion diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 2 is shown. Figure 14 The horizontal axis represents distortion, and its unit is percentage; Figure 14 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 14 The distortion curves of the large-aperture far-infrared optical system 100 provided in Example 2 at wavelengths of 8 micrometers, 10 micrometers, and 12 micrometers are shown respectively. Since the three curves almost completely overlap, this embodiment does not distinguish between the three curves. Figure 14 It can be seen that the maximum distortion of the large aperture far-infrared optical system 100 provided in Example 2 is -11.23%, which meets the requirements for clear imaging.

[0201] Please see Figure 15 , Figure 15 The relative illumination diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 2 is shown. Figure 15 The horizontal axis represents the image height, and its unit is millimeters. Figure 15 The vertical axis represents relative illumination. (From...) Figure 15 It can be seen that the relative illuminance of the large aperture far-infrared optical system 100 provided in Example 2 is greater than 74% within the entire field of view, and the brightness of the image is relatively uniform.

[0202] Please see Figure 16 , Figure 16 The diagram shows the transverse chromatic aberration of the large-aperture far-infrared optical system 100 provided in Example 2 under far-infrared light with wavelengths of 8 micrometers, 10 micrometers, and 12 micrometers. Figure 16 The x-axis represents the position of light rays of different wavelengths on the perpendicular image plane 80, in micrometers; Figure 16 The vertical axis represents the image height, and its unit is millimeters. Figure 16 The CCP presented three curves. The curve at 0 micrometers represents far-infrared light with a wavelength of 10 micrometers. Because the other two curves are too close together, they are not distinguished. Figure 16 It is known that the maximum transverse chromatic aberration is less than 3 micrometers across the entire field of view. Therefore, the large aperture far-infrared optical system 100 provided in Example 2 has good chromatic aberration correction capability.

[0203] Example 3

[0204] Figure 17 This diagram illustrates the architectural layout of the large-aperture far-infrared optical system 100 provided in Embodiment 3. Figure 17 The large-aperture far-infrared optical system 100, along the optical axis 90 from the object plane 70 to the image plane 80, includes, in sequence: a first aspherical lens 10, an aperture 50, a second aspherical lens 20, a diffractive optical element 40, a third aspherical lens 30, and a protective glass 60. The diffractive optical element 40 is a diffractive surface, which is disposed on the object-side surface of the third aspherical lens 30. Some parameters of the large-aperture far-infrared optical system 100 provided in Embodiment 3 are shown in Table 3-1.

[0205] Table 3-1. Partial parameters of the large-aperture far-infrared optical system 100 provided in Example 3

[0206]

[0207]

[0208] As shown in Table 3-1, the total optical length of the large-aperture far-infrared optical system 100 is relatively short, only 12.85 mm. Therefore, the large-aperture far-infrared optical system 100 provided in Example 3 has a relatively small volume. The large-aperture far-infrared optical system 100 has an F-number of 0.9, which allows for a large amount of light to enter, thus ensuring excellent imaging quality.

[0209] Along the optical axis 90 from the object plane 70 to the image plane 80, starting from the object plane 70, each surface in the large aperture far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain Table 3-2 below.

[0210] Table 3-2. Parameters of each surface in the large-aperture far-infrared optical system 100 provided in Example 3

[0211] Surface number Surface type Radius of curvature (mm) Thickness (mm) Material 0 flat unlimited unlimited - 1 even aspherical surface 5.16149 1.062 Chalcogenide Glass 2 even aspherical surface 4.41856 1.127 - 3 Aperture unlimited 0.862 - 4 even aspherical surface -17.74 2.002 Chalcogenide Glass 5 even aspherical surface -7.3558 0.827 - 6 even aspherical surface -6.7549 1.287 Chalcogenide Glass 7 even aspherical surface -6.2922 4.959 - 8 flat unlimited 0.625 silicon 9 flat unlimited 0.100 - 10 flat unlimited - -

[0212] For the analysis of each surface in Table 3-2, please refer to Example 1. This example will not analyze each surface again.

[0213] Surfaces 1, 2, 4, 5, 6, and 7 are all even-order aspherical surfaces, and their surface shapes satisfy the following relationship:

[0214]

[0215] Where Z(r) is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis 90°; c is the surface curvature of the aspherical surface, c = 1 / R, where R is the radius of curvature of the aspherical surface; k is the conic coefficient; A, B, C, D... are aspherical coefficients. The values ​​of k, A, B, C, D... for surfaces 1, 2, 4, 5, 6, and 7 can be found in Table 3-3.

[0216] Table 3-3. Coefficients of even-order aspherical surfaces in the large-aperture far-infrared optical system 100 provided in Example 3

[0217] surface k A B C D E 1 5.26E-01 -6.02E-04 -1.65E-04 2.45E-06 -7.70E-07 2.39E-08 2 -4.01E-01 3.09E-04 -5.74E-05 -3.39E-05 2.02E-06 -3.61E-08 4 1.75E+01 -2.27E-03 -4.49E-05 -2.94E-05 3.84E-06 -2.57E-07 5 1.04E-01 -3.62E-04 -5.26E-05 6.07E-07 1.29E-08 -2.06E-09 6 -3.66E-01 3.03E-03 -1.39E-04 8.66E-06 -1.86E-07 5.31E-10 7 -5.77E+00 -9.19E-04 2.93E-05 -1.14E-06 9.46E-08 -7.04E-10

[0218] The coefficients of each even-order aspheric surface of surfaces 1, 2, 4, 5, 6 and 7 can be found in Table 3-3. In this embodiment, the specific values ​​of each even-order aspheric surface coefficient will not be described in detail.

[0219] The diffraction plane is located on surface 6, and the phase expression of the diffraction plane is: Where ρ = r / r0, r is the radius of the diffraction surface, r0 is the normalized radius of the diffraction surface, and A i Here, represents the phase coefficient of the diffraction surface, and N is the number of terms in the polynomial. The coefficients of the diffraction surface can be found in Table 3-4.

[0220] Table 3-4. Coefficients of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Example 3

[0221] surface face shape Normalized radius A1 A2 A3 A4 6 Binary Diffraction Surface 4.2mm -7.01E+00 -6.62E+01 4.06E+01 8.77E+02

[0222] Please see Figure 18 , Figure 18 The phase distribution diagram of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Embodiment 3 is shown. Figure 18 The horizontal axis represents the distance from the center of the diffraction plane. Figure 18The vertical axis represents the phase. Since the phase is a periodic function of 2π, there exists a relationship... (where n is an integer), therefore Figure 18 The phase of the diffraction surface in Example 3 is normalized by taking the remainder of 2π to meet the actual processing requirements of the diffraction surface.

[0223] Please see Figure 19 , Figure 19 The MTF field-of-view curve of the large-aperture far-infrared optical system 100 provided in Embodiment 3 is shown. Figure 19 The horizontal axis represents the image height, meaning the horizontal axis measures the field of view using the image height, and the unit of the horizontal axis is millimeters. Figure 19 The vertical axis represents the MTF value. Figure 19 The table lists the sagittal curve S1 and meridional curve T1 for the MTF at a spatial frequency of 10 lp / mm as a function of field of view; the sagittal curve S2 and meridional curve T2 for the MTF at a spatial frequency of 21 lp / mm as a function of field of view; the sagittal curve S3 and meridional curve T3 for the MTF at a spatial frequency of 42 lp / mm as a function of field of view; and the sagittal curve S4 and meridional curve T4 for the MTF at a spatial frequency of 62.5 lp / mm as a function of field of view. Figure 19 It can be seen that at a spatial frequency of 62.5 lp / mm, the MTF is greater than 0.16 across the entire field of view, indicating that the large-aperture far-infrared optical system 100 has excellent imaging quality.

[0224] Please see Figure 20 , Figure 20 A dot plot of the large-aperture far-infrared optical system 100 provided in Embodiment 3 is shown. Figure 20 As can be seen, the maximum number of dots in the full field of view is less than 2 pixels (16 micrometers). Therefore, the light converges and is concentrated, and the large aperture far-infrared optical system 100 provided in Example 3 has a sharp imaging effect.

[0225] Please see Figure 21 , Figure 21 The field curvature diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 3 is shown. Figure 21 The horizontal axis represents the field curvature, and its unit is millimeters; Figure 21 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 21 In the diagram, S1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the sagittal direction, and T1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the meridional direction; S2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the sagittal direction, and T2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the meridional direction; S3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the sagittal direction, and T3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the meridional direction. Figure 21It can be seen that the field curvature of the large-aperture far-infrared optical system 100 in the sagittal direction is 0.1729 mm, and the field curvature of the large-aperture far-infrared optical system 100 in the meridional direction is 0.1092 mm, which meets the field curvature requirements of the excellent imaging quality standard.

[0226] Please see Figure 22 , Figure 22 The distortion diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 3 is shown. Figure 22 The horizontal axis represents distortion, and its unit is percentage; Figure 22 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 22 The distortion curves of the large-aperture far-infrared optical system 100 provided in Example 3 at wavelengths of 8 micrometers, 10 micrometers, and 12 micrometers are shown respectively. Since the three curves almost completely overlap, this embodiment does not distinguish between the three curves. Figure 22 It can be seen that the maximum distortion of the large aperture far-infrared optical system 100 provided in Example 3 is -11.60%, which meets the requirements for clear imaging.

[0227] Please see Figure 23 , Figure 23 The relative illumination diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 3 is shown. Figure 23 The horizontal axis represents the image height, and its unit is millimeters. Figure 23 The vertical axis represents relative illumination. (From...) Figure 23 It can be seen that the relative illuminance of the large aperture far-infrared optical system 100 provided in Example 3 is greater than 74% within the entire field of view, and the brightness of the image is relatively uniform.

[0228] Please see Figure 24 , Figure 24 The transverse chromatic aberration diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 3 is shown. Figure 24 The x-axis represents the position of light rays of different wavelengths on the perpendicular image plane 80, in micrometers; Figure 24 The vertical axis represents the image height, and its unit is millimeters. Figure 24 The CCP presented three curves: curve M1 is the vertical chromatic aberration curve for far-infrared light with a wavelength of 8 micrometers; curve M2, located at 0 micrometers on the horizontal axis, is the vertical chromatic aberration curve for far-infrared light with a wavelength of 10 micrometers; and curve M3 is the vertical chromatic aberration curve for far-infrared light with a wavelength of 12 micrometers. Figure 24 It is known that the maximum transverse chromatic aberration is less than 2 micrometers across the entire field of view. Therefore, the large aperture far-infrared optical system 100 provided in Example 3 has good chromatic aberration correction capability.

[0229] Example 4

[0230] Figure 25This diagram illustrates the architectural layout of the large-aperture far-infrared optical system 100 provided in Embodiment 4. Figure 25 The large-aperture far-infrared optical system 100, along the optical axis 90 from the object plane 70 to the image plane 80, includes, in sequence: a first aspherical lens 10, an aperture 50, a second aspherical lens 20, a diffractive optical element 40, a third aspherical lens 30, and a protective glass 60. The diffractive optical element 40 is a diffractive surface, which is disposed on the object-side surface of the third aspherical lens 30. Some parameters of the large-aperture far-infrared optical system 100 provided in Example 4 are shown in Table 4-1.

[0231] Table 4-1. Partial parameters of the large-aperture far-infrared optical system 100 provided in Example 4

[0232] Optical indicators Required value Effective focal length 5.865mm F number 1.0 distortion -9.47％ Relative Illuminance >81.2％ Total optical length (TTL) 12.88mm Optical Back Focus (BFL) 5.23mm Maximum field of view (FOV) (2ω) 62.465° Operating band 8μm-12μm

[0233] As shown in Table 4-1, the total optical length of the large-aperture far-infrared optical system 100 is relatively short, only 12.88 mm. Therefore, the large-aperture far-infrared optical system 100 provided in Example 4 has a relatively small volume. The large-aperture far-infrared optical system 100 has an F-number of 1.0, which allows for a large amount of light to enter, thereby ensuring excellent imaging quality.

[0234] Along the optical axis 90 from the object plane 70 to the image plane 80, starting from the object plane 70, each surface in the large aperture far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain Table 4-2 below.

[0235] Table 4-2. Parameters of each surface in the large-aperture far-infrared optical system 100 provided in Example 4

[0236]

[0237]

[0238] For the analysis of each surface in Table 4-2, please refer to Example 1. This example will not analyze each surface again.

[0239] Surfaces 1, 2, 4, 5, 6, and 7 are all even-order aspherical surfaces, and their surface shapes satisfy the following relationship:

[0240]

[0241] Where Z(r) is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis 90°; c is the surface curvature of the aspherical surface, c = 1 / R, where R is the radius of curvature of the aspherical surface; k is the conic coefficient; A, B, C, D... are aspherical coefficients. The values ​​of k, A, B, C, D... for surfaces 1, 2, 4, 5, 6, and 7 can be found in Table 4-3.

[0242] Table 4-3. Coefficients of even-order aspherical surfaces in the large-aperture far-infrared optical system 100 provided in Example 4

[0243] surface k A B C D E 1 -1.01E+00 -8.18E-04 6.24E-04 -2.30E-04 4.19E-05 -4.21E-06 2 7.26E-01 1.58E-03 -3.66E-03 2.24E-03 -7.82E-04 1.50E-04 4 8.38E+01 -2.87E-03 1.36E-03 -6.69E-04 1.50E-04 -1.63E-05 5 1.76E+00 6.89E-04 -3.86E-04 1.27E-04 -3.59E-05 5.28E-06 6 1.24E+00 2.85E-03 3.39E-05 -5.22E-05 5.07E-06 6.37E-07 7 5.49E-01 1.43E-03 -8.50E-05 1.00E-05 -8.57E-07 7.84E-08

[0244] The coefficients of each even-order aspheric surface of surfaces 1, 2, 4, 5, 6 and 7 can be found in Table 4-3. In this embodiment, the specific values ​​of each even-order aspheric surface coefficient will not be described in detail.

[0245] The diffraction plane is located on surface 6, and the phase expression of the diffraction plane is: Where ρ = r / r0, r is the radius of the diffraction surface, r0 is the normalized radius of the diffraction surface, and A i Here, represents the phase coefficient of the diffraction surface, and N is the number of terms in the polynomial. The coefficients of the diffraction surface can be found in Table 4-4.

[0246] Table 4-4. Coefficients of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Example 4

[0247] surface face shape Normalized radius A1 A2 A3 A4 6 Binary Diffraction Surface 3.4mm -1.09E+01 1.899 -8.591 -3.038E+01

[0248] Please see Figure 26 , Figure 26 The phase distribution diagram of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Embodiment 4 is shown. Figure 26 The horizontal axis represents the distance from the center of the diffraction plane. Figure 26 The vertical axis represents the phase. Since the phase is a periodic function of 2π, there exists a relationship... (where n is an integer), therefore Figure 26 The phase of the diffraction surface in Example 4 is normalized by taking the remainder of 2π to meet the actual processing requirements of the diffraction surface.

[0249] Please see Figure 27 , Figure 27 The MTF field-of-view curve of the large-aperture far-infrared optical system 100 provided in Embodiment 4 is shown. Figure 27 The horizontal axis represents the image height, meaning the horizontal axis measures the field of view using the image height, and the unit of the horizontal axis is millimeters. Figure 27 The vertical axis represents the MTF value. Figure 27The table lists the sagittal curve S1 and meridional curve T1 for the MTF at a spatial frequency of 10 lp / mm as a function of field of view; the sagittal curve S2 and meridional curve T2 for the MTF at a spatial frequency of 21 lp / mm as a function of field of view; the sagittal curve S3 and meridional curve T3 for the MTF at a spatial frequency of 42 lp / mm as a function of field of view; and the sagittal curve S4 and meridional curve T4 for the MTF at a spatial frequency of 62.5 lp / mm as a function of field of view. Figure 27 It can be seen that at a spatial frequency of 62.5 lp / mm, the MTF is greater than 0.16 across the entire field of view, indicating that the large-aperture far-infrared optical system 100 has excellent imaging quality.

[0250] Please see Figure 28 , Figure 28 A dot plot of the large-aperture far-infrared optical system 100 provided in Embodiment 4 is shown. Figure 28 As can be seen, the maximum number of dots in the full field of view is less than 2 pixels (16 micrometers). Therefore, the light converges and is concentrated, and the large aperture far-infrared optical system 100 provided in Example 4 has a sharp imaging effect.

[0251] Please see Figure 29 , Figure 29 The field curvature diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 4 is shown. Figure 29 The horizontal axis represents the field curvature, and its unit is millimeters; Figure 29 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 29 In the diagram, S1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the sagittal direction, and T1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the meridional direction; S2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the sagittal direction, and T2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the meridional direction; S3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the sagittal direction, and T3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the meridional direction. Figure 29 It can be seen that the field curvature of the large-aperture far-infrared optical system 100 in the sagittal direction is 0.1053 mm, and the field curvature of the large-aperture far-infrared optical system 100 in the meridional direction is 0.3185 mm, which meets the field curvature requirements of the excellent imaging quality standard.

[0252] Please see Figure 30 , Figure 30 The distortion diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 4 is shown. Figure 30 The horizontal axis represents distortion, and its unit is percentage; Figure 30 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 30 The distortion curves of the large-aperture far-infrared optical system 100 provided in Example 4 at wavelengths of 8 micrometers, 10 micrometers, and 12 micrometers are shown respectively. Since the three curves completely overlap, this embodiment does not distinguish between the three curves. Figure 30 It can be seen that the maximum distortion of the large aperture far-infrared optical system 100 provided in Example 4 is -9.46%, which meets the requirements for clear imaging.

[0253] Please see Figure 31 , Figure 31 The relative illumination diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 4 is shown. Figure 31 The horizontal axis represents the image height, and its unit is millimeters. Figure 31 The vertical axis represents relative illumination. (From...) Figure 31 It can be seen that the relative illuminance of the large aperture far-infrared optical system 100 provided in Example 4 is greater than 81% within the entire field of view, and the brightness of the image is relatively uniform.

[0254] Please see Figure 32 , Figure 32 The transverse chromatic aberration diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 4 is shown. Figure 32 The x-axis represents the position of light rays of different wavelengths on the perpendicular image plane 80, in micrometers; Figure 32 The vertical axis represents the image height, and its unit is millimeters. Figure 32 The CCP presented three curves: curve M1 is the vertical chromatic aberration curve for far-infrared light with a wavelength of 8 micrometers; curve M2, located at 0 micrometers on the horizontal axis, is the vertical chromatic aberration curve for far-infrared light with a wavelength of 10 micrometers; and curve M3 is the vertical chromatic aberration curve for far-infrared light with a wavelength of 12 micrometers. Figure 32 It is known that the maximum color difference between different wavelengths is less than 4 micrometers across the entire field of view. Therefore, the large aperture far-infrared optical system 100 provided in Example 4 has good color difference correction capability.

[0255] Example 5

[0256] Figure 33 This diagram illustrates the architectural layout of the large-aperture far-infrared optical system 100 provided in Embodiment 5. Figure 33 The large-aperture far-infrared optical system 100, along the optical axis 90 from the object plane 70 to the image plane 80, includes, in sequence: a first aspherical lens 10, an aperture 50, a second aspherical lens 20, a diffractive optical element 40, a third aspherical lens 30, and a protective glass 60. The diffractive optical element 40 is a diffractive surface, which is disposed on the object-side surface of the third aspherical lens 30. Some parameters of the large-aperture far-infrared optical system 100 provided in Embodiment 5 are shown in Table 5-1.

[0257] Table 5-1. Partial parameters of the large-aperture far-infrared optical system 100 provided in Example 5

[0258] Optical indicators Required value Effective focal length 5.924mm F number 1.0 distortion -9.2％ Relative Illuminance >82.3％ Total optical length (TTL) 13.44mm Optical Back Focus (BFL) 5.10mm Maximum field of view (FOV) (2ω) 61.780° Operating band 8μm-12μm

[0259] As shown in Table 5-1, the total optical length of the large-aperture far-infrared optical system 100 is relatively short, only 13.44 mm. Therefore, the large-aperture far-infrared optical system 100 provided in Example 5 has a relatively small volume. The large-aperture far-infrared optical system 100 has an F-number of 1.0, which allows for a large amount of light to enter, thereby ensuring excellent imaging quality.

[0260] Along the optical axis 90 from the object plane 70 to the image plane 80, starting from the object plane 70, each surface in the large aperture far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain Table 5-2 below.

[0261] Table 5-2. Parameters of various surfaces in the large-aperture far-infrared optical system 100 provided in Example 5

[0262] Surface number Surface type Radius of curvature (mm) Thickness (mm) Material 0 flat unlimited unlimited - 1 even aspherical surface 6.16 2.12 Chalcogenide Glass 2 even aspherical surface 5.15 0.70 - 3 Aperture unlimited 0.21 - 4 even aspherical surface -155.25 2.47 Chalcogenide Glass 5 even aspherical surface -9.05 0.24 - 6 even aspherical surface -6.09 2.60 Chalcogenide Glass 7 even aspherical surface -6.24 4.40 - 8 flat unlimited 0.60 silicon 9 flat unlimited 0.10 - 10 flat unlimited - -

[0263] For the analysis of each surface in Table 5-2, please refer to Example 1. This example will not analyze each surface again.

[0264] Surfaces 1, 2, 4, 5, 6, and 7 are all even-order aspherical surfaces, and their surface shapes satisfy the following relationship:

[0265]

[0266] Where Z(r) is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis 90°; c is the surface curvature of the aspherical surface, c = 1 / R, where R is the radius of curvature of the aspherical surface; k is the conic coefficient; A, B, C, D... are aspherical coefficients. The values ​​of k, A, B, C, D... for surfaces 1, 2, 4, 5, 6, and 7 can be found in Table 5-3.

[0267] Table 5-3. Coefficients of even-order aspherical surfaces in the large-aperture far-infrared optical system 100 provided in Example 5

[0268]

[0269]

[0270] The coefficients of each order of even-order aspherical surfaces 1, 2, 4, 5, 6 and 7 can be found in Table 5-3. In this embodiment, the specific values ​​of each order coefficient of even-order aspherical surfaces will not be described in detail.

[0271] The diffraction plane is located on surface 6, and the phase expression of the diffraction plane is: Where ρ = r / r0, r is the radius of the diffraction surface, r0 is the normalized radius of the diffraction surface, and A iHere, represents the phase coefficient of the diffraction surface, and N is the number of terms in the polynomial. The coefficients of the diffraction surface can be found in Table 5-4.

[0272] Table 5-4. Coefficients of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Example 5

[0273] surface face shape Normalized radius A1 A2 A3 A4 6 Binary Diffraction Surface 3.3mm -1.27E+01 1.92E+01 -1.16E+02 2.36E+02

[0274] Please see Figure 34 , Figure 34 The phase distribution diagram of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Embodiment 5 is shown. Figure 34 The horizontal axis represents the distance from the center of the diffraction plane. Figure 34 The vertical axis represents the phase. Since the phase is a periodic function of 2π, there exists a relationship... (where n is an integer), therefore Figure 34 The phase of the diffraction surface in Example 5 is normalized by taking the remainder of 2π to meet the actual processing requirements of the diffraction surface.

[0275] Please see Figure 35 , Figure 35 The MTF field-of-view curve of the large-aperture far-infrared optical system 100 provided in Embodiment 5 is shown. Figure 35 The horizontal axis represents the image height, meaning the horizontal axis measures the field of view using the image height, and the unit of the horizontal axis is millimeters. Figure 35 The vertical axis represents the MTF value. Figure 35 The table lists the sagittal curve S1 and meridional curve T1 for the MTF at a spatial frequency of 10 lp / mm as a function of field of view; the sagittal curve S2 and meridional curve T2 for the MTF at a spatial frequency of 21 lp / mm as a function of field of view; the sagittal curve S3 and meridional curve T3 for the MTF at a spatial frequency of 42 lp / mm as a function of field of view; and the sagittal curve S4 and meridional curve T4 for the MTF at a spatial frequency of 62.5 lp / mm as a function of field of view. Figure 35 It can be seen that at a spatial frequency of 62.5 lp / mm, the MTF is greater than 0.16 across the entire field of view, indicating that the large-aperture far-infrared optical system 100 has excellent imaging quality.

[0276] Please see Figure 36 , Figure 36 A dot plot of the large-aperture far-infrared optical system 100 provided in Embodiment 5 is shown. Figure 36 As can be seen, the maximum number of dots in the full field of view is less than 2 pixels (16 micrometers). Therefore, the light is concentrated and the imaging effect of the large aperture far-infrared optical system 100 provided in Example 5 is sharp.

[0277] Please see Figure 37 , Figure 37The field curvature diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 5 is shown. Figure 37 The horizontal axis represents the field curvature, and its unit is millimeters; Figure 37 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 37 In the diagram, S1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the sagittal direction, and T1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the meridional direction; S2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the sagittal direction, and T2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the meridional direction; S3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the sagittal direction, and T3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the meridional direction. Figure 37 It can be seen that the field curvature of the large-aperture far-infrared optical system 100 in the sagittal direction is 0.1116 mm, and the field curvature of the large-aperture far-infrared optical system 100 in the meridional direction is 0.2797 mm, which meets the field curvature requirements of the excellent imaging quality standard.

[0278] Please see Figure 38 , Figure 38 The distortion diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 5 is shown. Figure 38 The horizontal axis represents distortion, and its unit is percentage; Figure 38 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 38 The distortion curves of the large-aperture far-infrared optical system 100 provided in Example 5 at wavelengths of 8 micrometers, 10 micrometers, and 12 micrometers are shown respectively. Since the three curves completely overlap, this embodiment does not distinguish between the three curves. Figure 38 It can be seen that the maximum distortion of the large aperture far-infrared optical system 100 provided in Example 5 is -9.19%, which meets the requirements for clear imaging.

[0279] Please see Figure 39 , Figure 39 The relative illumination diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 5 is shown. Figure 39 The horizontal axis represents the image height, and its unit is millimeters. Figure 39 The vertical axis represents relative illumination. (From...) Figure 39 It can be seen that the relative illuminance of the large aperture far-infrared optical system 100 provided in Example 5 is greater than 82% within the entire field of view, and the brightness of the image is relatively uniform.

[0280] Please see Figure 40 , Figure 40 The transverse chromatic aberration diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 5 is shown. Figure 40 The x-axis represents the position of light rays of different wavelengths on the perpendicular image plane 80, in micrometers; Figure 40 The vertical axis represents the image height, and its unit is millimeters. Figure 40The CCP presented three curves: curve M1 is the vertical chromatic aberration curve for far-infrared light with a wavelength of 8 micrometers; curve M2, located at 0 micrometers on the horizontal axis, is the vertical chromatic aberration curve for far-infrared light with a wavelength of 10 micrometers; and curve M3 is the vertical chromatic aberration curve for far-infrared light with a wavelength of 12 micrometers. Figure 40 It is known that the maximum color difference between different wavelengths is less than 2 micrometers across the entire field of view. Therefore, the large aperture far-infrared optical system 100 provided in Example 5 has good color difference correction capability.

[0281] Example 6

[0282] Figure 41 This diagram illustrates the architectural layout of the large-aperture far-infrared optical system 100 provided in Embodiment 6. Figure 41 The large-aperture far-infrared optical system 100, along the optical axis 90 from the object plane 70 to the image plane 80, includes, in sequence: a first aspherical lens 10, an aperture 50, a second aspherical lens 20, a diffractive optical element 40, a third aspherical lens 30, and a protective glass 60. The diffractive optical element 40 is a diffractive surface, which is disposed on the object-side surface of the third aspherical lens 30. Some parameters of the large-aperture far-infrared optical system 100 provided in Embodiment 6 are shown in Table 6-1.

[0283] Table 6-1. Partial parameters of the large-aperture far-infrared optical system 100 provided in Example 6

[0284] Optical indicators Required value Effective focal length 5.822mm F number 1.0 distortion -8.6％ Relative Illuminance >81.2％ Total optical length (TTL) 11.89mm Optical Back Focus (BFL) 5.20mm Maximum field of view (FOV) (2ω) 61.730° Operating band 8μm-12μm

[0285] As shown in Table 6-1, the total optical length of the large-aperture far-infrared optical system 100 is relatively short, only 11.90 mm. Therefore, the large-aperture far-infrared optical system 100 provided in Example 6 has a relatively small volume. The large-aperture far-infrared optical system 100 has an F-number of 1.0, which allows for a large amount of light to enter, thereby ensuring excellent imaging quality.

[0286] Along the optical axis 90 from the object plane 70 to the image plane 80, starting from the object plane 70, each surface in the large aperture far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain Table 6-2 below.

[0287] Table 6-2. Parameters of each surface in the large-aperture far-infrared optical system 100 provided in Example 6

[0288]

[0289]

[0290] For the analysis of each surface in Table 6-2, please refer to Example 1. This example will not analyze each surface again.

[0291] Surfaces 1, 2, 4, 5, 6, and 7 are all even-order aspherical surfaces, and their surface shapes satisfy the following relationship:

[0292]

[0293] Where Z(r) is the distance vector from the vertex of the aspherical surface at a height of r along the optical axis 90°; c is the surface curvature of the aspherical surface, c = 1 / R, where R is the radius of curvature of the aspherical surface; k is the conic coefficient; A, B, C, D... are aspherical coefficients. The values ​​of k, A, B, C, D... for surfaces 1, 2, 4, 5, 6, and 7 can be found in Table 6-3.

[0294] Table 6-3. Coefficients of even-order aspherical surfaces in the large-aperture far-infrared optical system 100 provided in Example 6

[0295] surface k A B C D E 1 -2.74E-01 -2.73E-04 6.72E-04 -2.64E-04 5.07E-05 -5.25E-06 2 1.54E+00 3.52E-03 -4.56E-03 2.34E-03 -7.82E-04 1.49E-04 4 9.44E+01 -3.97E-03 1.43E-03 -7.67E-04 1.71E-04 -1.71E-05 5 1.38E+00 6.60E-04 -5.78E-04 1.62E-04 -4.15E-05 5.97E-06 6 9.19E-01 4.29E-03 9.89E-05 -9.51E-05 1.64E-05 -2.74E-07 7 4.57E-01 2.24E-03 -1.05E-04 1.54E-05 -1.23E-06 1.71E-07

[0296] The coefficients of each order of even-order aspherical surfaces of surfaces 1, 2, 4, 5, 6 and 7 can be found in Table 6-3. In this embodiment, the specific values ​​of each order of coefficients of even-order aspherical surfaces will not be described in detail.

[0297] The diffraction plane is located on surface 6, and the phase expression of the diffraction plane is: Where ρ = r / r0, r is the radius of the diffraction surface, r0 is the normalized radius of the diffraction surface, and A i Here, represents the phase coefficient of the diffraction surface, and N is the number of terms in the polynomial. The coefficients of the diffraction surface can be found in Table 6-4.

[0298] Table 6-4. Coefficients of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Example 6

[0299] surface face shape Normalized radius A1 A2 A3 A4 6 Binary Diffraction Surface 3.3mm -2.31E+01 7.06E+01 -2.45E+02 4.43E+02

[0300] Please see Figure 42 , Figure 42 The phase distribution diagram of the diffraction surface in the large-aperture far-infrared optical system 100 provided in Embodiment 6 is shown. Figure 42 The horizontal axis represents the distance from the center of the diffraction plane. Figure 42 The vertical axis represents the phase. Since the phase is a periodic function of 2π, there exists a relationship... (where n is an integer), therefore Figure 42 The phase of the diffraction surface in Example 6 is normalized by taking the remainder of 2π to meet the actual processing requirements of the diffraction surface.

[0301] Please see Figure 43 , Figure 43 The MTF field-of-view curve of the large-aperture far-infrared optical system 100 provided in Embodiment 6 is shown. Figure 43 The horizontal axis represents the image height, meaning the horizontal axis measures the field of view using the image height, and the unit of the horizontal axis is millimeters. Figure 43 The vertical axis represents the MTF value. Figure 43 The table lists the sagittal curve S1 and meridional curve T1 for the MTF at a spatial frequency of 10 lp / mm as a function of field of view; the sagittal curve S2 and meridional curve T2 for the MTF at a spatial frequency of 21 lp / mm as a function of field of view; the sagittal curve S3 and meridional curve T3 for the MTF at a spatial frequency of 42 lp / mm as a function of field of view; and the sagittal curve S4 and meridional curve T4 for the MTF at a spatial frequency of 62.5 lp / mm as a function of field of view. Figure 43 It can be seen that at a spatial frequency of 62.5 lp / mm, the MTF is greater than 0.15 across the entire field of view, indicating that the large-aperture far-infrared optical system 100 has excellent imaging quality.

[0302] Please see Figure 44 , Figure 44 A dot plot of the large-aperture far-infrared optical system 100 provided in Embodiment 6 is shown. Figure 44 As can be seen, the maximum number of dots in the full field of view is less than 2 pixels (16 micrometers). Therefore, the light converges and is concentrated, and the large aperture far-infrared optical system 100 provided in Example 6 has a sharp imaging effect.

[0303] Please see Figure 45 , Figure 45 The field curvature diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 6 is shown. Figure 45 The horizontal axis represents the field curvature, and its unit is millimeters; Figure 45 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 45 In the diagram, S1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the sagittal direction, and T1 represents the field curvature of 8-micrometer-wavelength far-infrared light in the meridional direction; S2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the sagittal direction, and T2 represents the field curvature of 10-micrometer-wavelength far-infrared light in the meridional direction; S3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the sagittal direction, and T3 represents the field curvature of 12-micrometer-wavelength far-infrared light in the meridional direction. Figure 45 It can be seen that the field curvature of the large-aperture far-infrared optical system 100 in the sagittal direction is 0.2611 mm, and the field curvature of the large-aperture far-infrared optical system 100 in the meridional direction is 0.5365 mm, which meets the field curvature requirements of the excellent imaging quality standard.

[0304] Please see Figure 46 , Figure 46 The distortion diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 6 is shown. Figure 46 The horizontal axis represents distortion, and its unit is percentage; Figure 46 The vertical axis represents the field of view angle along the Y-axis, and its unit is degrees. Figure 46 The distortion curves of the large-aperture far-infrared optical system 100 provided in Example 6 at wavelengths of 8 micrometers, 10 micrometers, and 12 micrometers are shown respectively. Since the three curves completely overlap, this embodiment does not distinguish between the three curves. Figure 46 It can be seen that the maximum distortion of the large aperture far-infrared optical system 100 provided in Example 6 is -8.60%, which meets the requirements for clear imaging.

[0305] Please see Figure 47 , Figure 47 The relative illumination diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 6 is shown. Figure 47 The horizontal axis represents the image height, and its unit is millimeters. Figure 47 The vertical axis represents relative illumination. (From...) Figure 47 It can be seen that the relative illuminance of the large aperture far-infrared optical system 100 provided in Example 6 is greater than 81% within the entire field of view, and the brightness of the image is relatively uniform.

[0306] Please see Figure 48 , Figure 48 The transverse chromatic aberration diagram of the large-aperture far-infrared optical system 100 provided in Embodiment 6 is shown. Figure 48 The x-axis represents the position of light rays of different wavelengths on the perpendicular image plane 80, in micrometers; Figure 48 The vertical axis represents the image height, and its unit is millimeters. Figure 48 The CCP presented three curves: curve M1 is the vertical chromatic aberration curve for far-infrared light with a wavelength of 8 micrometers; curve M2, located at 0 micrometers on the horizontal axis, is the vertical chromatic aberration curve for far-infrared light with a wavelength of 10 micrometers; and curve M3 is the vertical chromatic aberration curve for far-infrared light with a wavelength of 12 micrometers. Figure 48 It is known that the maximum color difference between different wavelengths is less than 4 micrometers across the entire field of view. Therefore, the large aperture far-infrared optical system 100 provided in Example 6 has good color difference correction capability.

[0307] After summarizing the parameters of the large-aperture far-infrared optical system 100 provided in the above six embodiments, Table 7 is shown below. The table 7 is mainly used to illustrate that the conditions satisfied by the large-aperture far-infrared optical system 100 provided in this application have all been experimentally verified and supported.

[0308] Table 7. Parameters of the large-aperture far-infrared optical system 100 provided in each embodiment

[0309]

[0310]

[0311]

[0312] This application also provides a large-aperture far-infrared optical lens (not shown). The large-aperture far-infrared optical lens includes an imaging detector (not shown) and the aforementioned large-aperture far-infrared optical system 100. The specific architecture of the large-aperture far-infrared optical system 100 can be found above and will not be repeated here. The imaging detector is located on the image plane 80 of the large-aperture far-infrared optical system 100. The imaging detector includes, but is not limited to, CMOS (Complementary Metal Oxide Semiconductor) and CCD (Charge Coupled Device).

[0313] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this application are indicated by the appended claims.

Claims

1. A large-aperture far-infrared optical system, characterized in that, The large-aperture far-infrared optical system includes: The first aspherical lens has an object-side surface convex towards the object side and an image-side surface convex towards the object side. The second aspherical lens has a positive optical power, and its object side convexes towards the image side, while its image side convexes towards the image side. The third aspherical lens has a positive optical power, and its object side convexes towards the image side, while its image side convexes towards the image side. A diffractive optical element is disposed in the optical path of the large-aperture far-infrared optical system; The first aspherical lens, the second aspherical lens, and the third aspherical lens are arranged sequentially along the optical axis from the object side to the image side; the large-aperture far-infrared optical system satisfies: |f2|<|f3|<|f1|, where f1 is the focal length of the first aspherical lens, f2 is the focal length of the second aspherical lens, and f3 is the focal length of the third aspherical lens.

2. The large-aperture far-infrared optical system according to claim 1, characterized in that, The large aperture far-infrared optical system also includes an aperture stop, which is disposed in the optical path of the large aperture far-infrared optical system; The large-aperture far-infrared optical system satisfies: Wherein, f is the effective focal length of the large-aperture far-infrared optical system, and D... S The aperture of the aperture stop is denoted by , the total optical length of the large aperture far-infrared optical system is denoted by TTL, and the maximum field of view of the large aperture far-infrared optical system is denoted by FOV.

3. The large-aperture far-infrared optical system according to claim 1, characterized in that, The large-aperture far-infrared optical system satisfies:

4. The large-aperture far-infrared optical system according to claim 1, characterized in that, The large-aperture far-infrared optical system satisfies: Wherein, FOV is the maximum field of view of the large aperture far-infrared optical system, and f is the effective focal length of the large aperture far-infrared optical system.

5. The large-aperture far-infrared optical system according to claim 1, characterized in that, The large aperture far-infrared optical system also includes an aperture stop, which is disposed in the optical path of the large aperture far-infrared optical system; The large-aperture far-infrared optical system satisfies: Wherein, D1 is the maximum effective diameter of the first aspherical lens, D2 is the maximum effective diameter of the second aspherical lens, D3 is the maximum effective diameter of the third aspherical lens, and D... S The aperture of the aperture is denoted as .

6. The large-aperture far-infrared optical system according to claim 1, characterized in that, The large-aperture far-infrared optical system satisfies: Wherein, D1 is the maximum effective diameter of the first aspherical lens, D2 is the maximum effective diameter of the second aspherical lens, and D3 is the maximum effective diameter of the third aspherical lens.

7. The large-aperture far-infrared optical system according to claim 1, characterized in that, The large-aperture far-infrared optical system satisfies: Wherein, Imgh is half the diagonal length of the image formed by the large aperture far-infrared optical system at the maximum field of view, n1 is the refractive index of the first aspherical lens, FOV is the maximum field of view of the large aperture far-infrared optical system, FNO is the aperture number of the large aperture far-infrared optical system, and R1 is the radius of curvature of the object side surface of the first aspherical lens.

8. The large-aperture far-infrared optical system according to claim 1, characterized in that, The large-aperture far-infrared optical system satisfies: Wherein, the f 12 The combined focal length of the first aspherical lens and the second aspherical lens is f. 23 The combined focal length of the second aspherical lens and the third aspherical lens.

9. The large-aperture far-infrared optical system according to any one of claims 1-8, characterized in that, The diffractive optical element is a diffractive surface, which is disposed on the object-side surface of the third aspherical lens.

10. A large-aperture far-infrared optical lens, characterized in that, The large-aperture far-infrared optical lens includes: an imaging detector and a large-aperture far-infrared optical system as described in any one of claims 1-9; the imaging detector is disposed on the image plane of the large-aperture far-infrared optical system.

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