A far-infrared optical system and a far-infrared optical lens

Abstract

The present application discloses a far-infrared optical system and a far-infrared optical lens. The far-infrared optical system includes a super lens and an aspheric lens in sequence from the object side to the image side along the optical axis. The optical power of the super lens is positive; the optical power of the aspheric lens is positive, and the surface of the aspheric lens close to the object side and the surface close to the image side are both convex to the image side. The far-infrared optical system satisfies: #imgabs0# where Φ2 is the optical power of the aspheric lens, Φ m is the focal length of the metalens. In the present application, by reasonably allocating the focal length of the metalens and the aspheric lens, the aspheric lens is mainly used to bear the focal length, and the metalens is mainly used to correct aberrations, so that the far-infrared optical system has better imaging quality. In addition, by reasonably allocating the focal length, the far-infrared optical system has good processability and can be easily manufactured. In batch manufacturing, the cost of a single metalens is low, so the production cost of the far-infrared optical system can be reduced to a certain extent.

Description

Technical Field

[0001] The present application relates to the field of optical systems, and in particular to a far-infrared optical system and a far-infrared optical lens. Background Art

[0002] In the prior art, in the field of far-infrared optical systems, in order to improve imaging quality, multiple aspheric lenses are usually used to control aberrations. However, the use of multiple aspheric lenses will cause the far-infrared optical system to have problems of high cost and poor processability. Utility Model Content

[0003] In response to the above technical problems, the embodiments of the present application provide a far-infrared optical system and a far-infrared optical lens, aiming to provide a far-infrared optical system and a far-infrared optical lens with low cost, good processability and better imaging quality.

[0004] According to one aspect of an embodiment of the present application, a far-infrared optical system is disclosed, and the far-infrared optical system includes, in order from the object side to the image side along the optical axis: a super lens and an aspheric lens, wherein the optical focal length of the super lens is positive; the optical focal length of the aspheric lens is positive, the surface of the aspheric lens close to the object side is convex toward the image side, and the surface of the aspheric lens close to the image side is convex toward the image side;

[0005] Wherein, the far-infrared optical system satisfies: Wherein Φ2 is the focal length of the aspheric lens, and Φ m is the optical power of the metalens.

[0006] In some embodiments, the far-infrared optical system satisfies: Among them, the f m is the focal length of the superlens, and f is the effective focal length of the far-infrared optical system.

[0007] In some embodiments, the far-infrared optical system satisfies: Wherein, Δλ is the maximum wavelength difference of the working band of the far-infrared optical system, is the phase of the superlens, and x is the distance between any point on the superlens and the center of the superlens.

[0008] In some embodiments, the far-infrared optical system satisfies: Among them, T2 is the center thickness of the aspheric lens, R1 is the curvature radius of the surface of the aspheric lens close to the object side, K1 is the cone coefficient of the surface of the aspheric lens close to the object side, R2 is the curvature radius of the surface of the aspheric lens close to the image side, and K2 is the cone coefficient of the surface of the aspheric lens close to the image side.

[0009] In some embodiments, the far-infrared optical system satisfies: Among them, n is the refractive index of the material of the aspheric lens, the EPD is the entrance pupil diameter of the far-infrared optical system, R2 is the curvature radius of the surface of the aspheric lens close to the image side, and K2 is the cone coefficient of the surface of the aspheric lens close to the image side.

[0010] In some embodiments, the far-infrared optical system satisfies: Among them, the T m is the center thickness of the super lens, T2 is the center thickness of the aspheric lens, and T m2 is the thickness of the air gap between the superlens and the aspheric lens on the optical axis.

[0011] In some embodiments, the far-infrared optical system satisfies: Wherein, f2 is the focal length of the aspheric lens, and T2 is the thickness of the aspheric lens on the optical axis.

[0012] In some embodiments, the far-infrared optical system satisfies: Wherein, R1 is the curvature radius of the surface of the aspheric lens close to the object side, and R2 is the curvature radius of the surface of the aspheric lens close to the image side.

[0013] In some embodiments, the far-infrared optical system satisfies: Among them, the F# is the aperture number of the far-infrared optical system, and the FOV is the maximum field of view angle of the far-infrared optical system.

[0014] In some embodiments, the far-infrared optical system further includes an aperture, and the aperture is located between the superlens and the aspheric lens; or, the aperture is located on a side of the superlens away from an image plane of the far-infrared optical system.

[0015] In some embodiments, the aperture is disposed on a surface of the superlens close to the image side.

[0016] A second aspect of an embodiment of the present application provides a far-infrared optical lens, comprising an imaging detector and a far-infrared optical system as described in any one of the above items; the imaging detector is arranged on the image plane of the far-infrared optical system.

[0017] The far-infrared optical system provided by the present application includes a super lens and an aspheric lens in sequence from the object side to the image side along the optical axis, the optical power of the super lens is positive; the optical power of the aspheric lens is positive, the surface of the aspheric lens close to the object side is convex to the image side, and the surface of the aspheric lens close to the image side is convex to the image side. Among them, the far-infrared optical system satisfies: Where Φ2 is the focal length of the aspheric lens, Φ m is the optical power of the metalens. In the present application, by reasonably allocating the optical power of the metalens and the aspheric lens, the aspheric lens bears the main optical power in the far-infrared optical system, and the metalens is mainly used to correct aberrations in the far-infrared optical system so that the far-infrared optical system has better imaging quality. In addition, by reasonably allocating the optical power, the far-infrared optical system has good processability and can be easily manufactured. Since the cost of a single metalens is low during batch manufacturing, the production cost of the far-infrared optical system can be reduced to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and other objects, features and advantages of the present application will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings.

[0019] Figure 1 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0020] Figure 2 Shows Figure 1 Enlarged schematic diagram of point P in the middle.

[0021] Figure 3 The MTF field of view curve of the far-infrared optical system in one embodiment of the present application is shown.

[0022] Figure 4 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0023] Figure 5 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0024] Figure 6 A vertical axis chromatic aberration diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0025] Figure 7 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0026] Figure 8 The MTF field of view curve of the far-infrared optical system in one embodiment of the present application is shown.

[0027] Fig. 9 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0028] Fig.10 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0029] Fig.11 A vertical axis chromatic aberration diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0030] Fig.12 A schematic diagram of the architecture layout of a far-infrared optical system in an embodiment of the present application is shown.

[0031] Fig.13 The MTF field of view curve of the far-infrared optical system in one embodiment of the present application is shown.

[0032] Fig.14 A field curvature diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0033] Fig.15 A distortion diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0034] Fig.16 A vertical axis chromatic aberration diagram of a far-infrared optical system in an embodiment of the present application is shown.

[0035] Reference numerals

[0036] 100. Far infrared optical system;

[0037] 1. Superlens; 11. Substrate; 12. Micro-nanostructure;

[0038] 2. Aspheric lens;

[0039] 3. Aperture;

[0040] 4. Protective parts;

[0041] A, object plane; B, image plane; S, optical axis. DETAILED DESCRIPTION

[0042] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these example embodiments are provided so that the description of the present application will be more comprehensive and complete and the concepts of the example embodiments will be fully conveyed to those skilled in the art. The accompanying drawings are only schematic illustrations of the present application and are not necessarily drawn to scale. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.

[0043] In addition, the described features, structures or characteristics may be combined in one or more example embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the example embodiments of the present application. However, those skilled in the art will appreciate that the technical solution of the present application may be practiced while omitting one or more of the specific details, or other modules, components, etc. may be adopted. In other cases, known structures, methods, implementations or operations are not shown or described in detail to avoid obscuring the present application and making the various aspects of the present application obscure.

[0044] See also Figure 1 , Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of a far-infrared optical system 100 in an embodiment of the present application, wherein the optical axis S is the center line of the light beam. Figure 1 In the figure, the object to be measured is located on the left side of the leftmost lens, that is, the object side is located on the left side of the leftmost lens, and the object plane A is located on the object side. The image formed by the far-infrared optical system 100 is located on the right side of the rightmost lens, that is, the image side is located on the right side of the rightmost lens, and the image plane B is located on the image side. Therefore, the direction from the object plane A to the image plane B along the optical axis S is consistent with the direction from the object side to the image side along the optical axis S.

[0045] The far-infrared optical system 100 includes a super lens 1 and an aspherical lens 2 , and the super lens 1 and the aspherical lens 2 are sequentially arranged along the optical axis S from the object side to the image side.

[0046] The optical focal length of the superlens 1 is positive. The superlens 1 includes a substrate 11 and a micro-nano structure 12. At least one of the surface of the substrate 11 close to the object side and the surface of the substrate 11 close to the image side is provided with the micro-nano structure 12. According to the phase modulation method adopted, the corresponding phase modulation formula can be adaptively used to configure the various parameters of the micro-nano structure 12, so that the superlens 1 can achieve the corresponding optical performance. The superlens 1 can be manufactured by semiconductor technology. In mass production, the cost of a single superlens 1 is low, which can reduce the production cost of the far-infrared optical system 100.

[0047] The optical power of the aspheric lens 2 is positive, the surface of the aspheric lens 2 close to the object side is convex toward the image side, and the surface of the aspheric lens 2 close to the image side is convex toward the image side, that is, the aspheric lens 2 is a positive meniscus lens.

[0048] The far-infrared optical system 100 satisfies conditional formula 1: Where Φ2 is the focal length of aspheric lens 2, Φ m is the focal length of superlens 1. Φ2 and Φ m The units are the same, for example mm -1Conditional formula 1 indicates that the focal power of the metalens 1 is much smaller than that of the aspheric lens 2. The focal power of the metalens 1 and the aspheric lens 2 can be reasonably matched by conditional formula 1, so that both the metalens 1 and the aspheric lens 2 have expected focal powers, and the far-infrared optical system 100 can have expected deflection capability for incident light, and can also have good processability.

[0049] In the present application, by reasonably allocating the optical power of the metalens 1 and the aspheric lens 2, the aspheric lens 2 bears the main optical power in the far-infrared optical system 100, and the metalens 1 is mainly used to correct aberrations in the far-infrared optical system 100, so that the far-infrared optical system 100 has better imaging quality. In addition, by reasonably allocating the optical power, the far-infrared optical system 100 has good machinability and can be easily produced. Since the cost of a single metalens 1 is relatively low during batch manufacturing, the production cost of the far-infrared optical system 100 can be reduced to a certain extent. That is, the far-infrared optical system 100 provided by the present application has the advantages of low cost, good machinability, and better imaging quality.

[0050] Furthermore, in some embodiments, the far-infrared optical system 100 satisfies conditional formula 2: The optical power of the metalens 1 and the aspherical lens 2 can be more accurately distributed through the conditional expression 2, so that the far-infrared optical system 100 can perform better in aberration control, thereby making the imaging quality of the far-infrared optical system 100 better.

[0051] In some embodiments, the micro-nano structure 12 is disposed on a surface of the substrate 11 close to the object side.

[0052] In some embodiments, the surface of the substrate 11 close to the object side and the surface of the substrate 11 close to the image side are both provided with micro-nano structures 12, so that the superlens 1 has a higher degree of design freedom.

[0053] In some embodiments, the micro-nano structure 12 is a positive micro-nano structure 12 .

[0054] In some embodiments, the micro-nano structure 12 is a negative micro-nano structure 12 .

[0055] In some embodiments, the micro-nano structure 12 is provided with a layer to make the processing technology of the superlens 1 compatible with the existing semiconductor processing technology, which can facilitate the processing and manufacturing of the superlens 1.

[0056] In some embodiments, the micro-nano structure 12 has two or more layers, so that the superlens 1 has a larger and expected optical focal length.

[0057] For the superlens 1, the position of the micro-nano structure 12, the positive and negative of the micro-nano structure 12, and the number of layers of the micro-nano structure 12 can be freely combined as long as the superlens 1 has the expected performance.

[0058] In some embodiments, the specific structure of the metalens 1 is as follows: the micro-nano structure 12 is provided on the surface of the substrate 11 close to the image side, and the micro-nano structure 12 is a negative micro-nano structure 12, and the micro-nano structure 12 is provided with only one layer, so that the metalens 1 has good processability and also has an optical focal length that meets expectations. It should be noted that this is only used for illustration and should not be understood as a limitation on the specific structure of the metalens 1.

[0059] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 3: Among them, f m is the focal length of the superlens 1, and f is the effective focal length of the far-infrared optical system 100. m , f have the same dimension, both are length units, such as millimeters.

[0060] Conditional formula three indicates that the optical focal length provided by the metalens 1 in the far-infrared optical system 100 is much smaller than that of the far-infrared optical system 100, and the main function of the metalens 1 is to provide aberration compensation in the full field of view. The upper limit of conditional formula three is used to ensure that the metalens 1 has the expected optical focal length, so that the metalens 1 can complete the light adjustment within the system length, and ensure that the metalens 1 has the ability to compensate for aberrations. The lower limit of conditional formula three is used to avoid excessive optical focal length of the metalens 1. Excessive optical focal length of the metalens 1 will lead to overcompensation, which will introduce dispersion. The greater the overcompensation, the greater the dispersion of the far-infrared optical system 100.

[0061] In some embodiments, the far-infrared optical system 100 satisfies Condition 4: Wherein, Δλ is the difference between the maximum operating wavelength and the minimum operating wavelength of the far-infrared optical system 100. x is the distance between any point on the metalens 1 and the center of the metalens 1, and dx represents the change in the distance between any point on the metalens 1 and the center of the metalens 1. dx and Δλ have the same dimension, both of which are length units, such as millimeters. is the phase of superlens 1, represents the phase change of the superlens 1, The unit of is rad, and the unit of "2π" in conditional expression 2 is also rad. Since the focal lengths provided by the superlens 1 for light of different wavelengths are slightly different, the larger Δλ is, the greater the negative chromatic aberration brought by the superlens 1 with the same phase gradient is. is the maximum value of the phase gradient of the structural surface of the superlens 1, where It reflects the magnitude of negative chromatic aberration introduced by the structural surface of the superlens 1.

[0062] In order to control the aberration of the far-infrared optical system 100, the phase distribution slope of the structural surface of the metalens 1 must satisfy conditional expression 4. The upper limit of conditional expression 4 can ensure that the positive chromatic aberration brought by the aspheric lens 2 can be compensated by the metalens 1, and the lower limit of conditional expression 4 can avoid the metalens 1 introducing a large chromatic aberration and causing over-compensation.

[0063] In some embodiments, the far-infrared optical system 100 satisfies Condition 5: Wherein, T2 is the center thickness of the aspheric lens 2, R1 is the curvature radius of the surface of the aspheric lens 2 close to the object side, K1 is the conic coefficient of the surface of the aspheric lens 2 close to the object side, R2 is the curvature radius of the surface of the aspheric lens 2 close to the image side, and K2 is the conic coefficient of the surface of the aspheric lens 2 close to the image side. T2, R1, and R2 have the same dimension, which is a length unit, such as millimeters.

[0064] In the present application, the aspheric lens 2 is a meniscus lens, and the conditional formula 5 is used to ensure that the surface of the aspheric lens 2 close to the object side and the surface of the aspheric lens 2 close to the image side have a suitable radius of curvature and a cone coefficient, thereby ensuring that the aspheric lens 2 has a suitable optical power. At the same time, a reasonable cone coefficient has the effect of improving the imaging quality, and a reasonable cone coefficient can make the aspheric lens 2 have a suitable thickness, which can ensure that the surface of the aspheric lens 2 close to the object side and the surface of the aspheric lens 2 close to the image side do not overlap.

[0065] In some embodiments, the far-infrared optical system 100 satisfies conditional formula 6: Wherein, n is the refractive index of the material of the aspheric lens 2, the EPD (Entrance Pupil Diameter, referred to as EPD) is the entrance pupil diameter of the far-infrared optical system 100, R2 is the curvature radius of the surface of the aspheric lens 2 close to the image side, and K2 is the cone coefficient of the surface of the aspheric lens 2 close to the image side. EPD and R2 have the same dimension, both of which are length units, such as millimeters.

[0066] Conditional formula 6 can ensure that the incident angle and the aperture of the far-infrared optical system 100 are within a reasonable range. The ratio of conditional formula 6 directly affects the aperture of the far-infrared optical system 100. Since the aperture of the far-infrared optical system 100 is smaller than the aperture of the far-infrared optical system 100, the upper limit and lower limit of conditional formula 6 can be used to constrain the aperture of the far-infrared optical system 100, so that the volume of the far-infrared optical system 100 can be compressed.

[0067] In some embodiments, the far-infrared optical system 100 satisfies conditional equation 7: Among them, the T mis the center thickness of the metalens 1, and T2 is the center thickness of the aspheric lens 2. In this application, the thickness of the lens is the thickness of the lens on the optical axis S. m2 is the thickness of the air gap between the super lens 1 and the aspheric lens 2 on the optical axis S. For ease of description, the thickness of the air gap between the super lens 1 and the aspheric lens 2 on the optical axis S is referred to as the air gap thickness below. m , T2, T m2 have the same dimension, which is a unit of length, such as millimeter.

[0068] Conditional formula 7 reflects the ratio of the total optical length of the far-infrared optical system 100 to the thickness of the air gap. The upper limit of conditional formula 7 is used to constrain the thickness of the air gap. The upper limit of conditional formula 7 can avoid the thickness of the air gap being too large, leaving enough installation space for the metalens 1 and the aspheric lens 2. In addition, the upper limit of conditional formula 7 can also ensure that the far-infrared optical system 100 has a sufficient optical back focal length, which can facilitate the assembly of the far-infrared optical system 100. The lower limit of conditional formula 7 ensures that there is a reasonable spacing between the metalens 1 and the aspheric lens 2, so that the far-infrared optical system 100 has the advantage of being easy to assemble.

[0069] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 8: Wherein, f2 is the focal length of the aspheric lens 2, and T2 is the thickness of the aspheric lens 2 on the optical axis S. f2 and T2 have the same dimension, both of which are length units, such as millimeters.

[0070] The upper limit of conditional expression 8 is used to ensure that the aspheric lens 2 has a suitable optical focal length, so that the size of the imaging area of ​​the far-infrared optical system 100 is compatible with the size of the corresponding image sensor. The lower limit of conditional expression 8 can prevent the thickness of the aspheric lens 2 from being too large. If the thickness of the aspheric lens 2 is too large, more lens material will be consumed, which will lead to a higher material cost of the aspheric lens 2.

[0071] In some embodiments, the far-infrared optical system 100 satisfies Condition 9: Wherein, R1 is the curvature radius of the surface of the aspheric lens 2 close to the object side, and R2 is the curvature radius of the surface of the aspheric lens 2 close to the image side. R1 and R2 have the same dimension, both of which are length units, such as millimeters.

[0072] Conditional Formula 9 reflects the ratio of the radius of curvature of the surface of the aspheric lens 2 close to the object side to the radius of curvature of the surface of the aspheric lens 2 close to the image side. Conditional Formula 9 can ensure that the curvature of the surface of the aspheric lens 2 close to the object side and the curvature of the surface of the aspheric lens 2 close to the image side have appropriate sizes, thereby ensuring that the aspheric lens 2 has good processability.

[0073] In some embodiments, the far-infrared optical system 100 satisfies Conditional Formula 10: The F# is the aperture number of the far-infrared optical system 100, that is, the F number. The FOV (Field of View, FOV for short) is the maximum field of view of the far-infrared optical system 100.

[0074] Conditional formula 10 reflects the ratio of the aperture number of the far-infrared optical system 100 to the tangent value of the maximum half-viewing angle of the far-infrared optical system 100. Conditional formula 10 constrains the aperture of the far-infrared optical system 100 and avoids the far-infrared optical system 100 from being too large. At the same time, conditional formula 10 also ensures the image height corresponding to a certain incident angle, so that the far-infrared optical system 100 and the corresponding image sensor have good adaptability.

[0075] In some embodiments, the far-infrared optical system 100 further includes an aperture 3, which is used to control the amount of light entering the far-infrared optical system 100, ensuring that the far-infrared optical system 100 can work effectively and generate high-quality images. The aperture 3 is located between the superlens 1 and the aspheric lens 2, wherein the aperture 3 is located between the superlens 1 and the aspheric lens 2, including the case where the aperture 3 is arranged on the surface of the superlens 1 or the surface of the aspheric lens 2. Alternatively, the aperture 3 is located on the side of the superlens 1 away from the image plane B.

[0076] In some embodiments, the aperture 3 is disposed on the object side of the superlens 1 , that is, the aperture 3 is located on the side of the superlens 1 away from the aspheric lens 2 , and there is a preset distance between the aperture 3 and the superlens 1 .

[0077] In some embodiments, the aperture 3 is disposed on a surface of the superlens 1 close to the object side, that is, the aperture 3 is disposed on the front surface of the superlens 1 .

[0078] In some embodiments, see Figure 1 and Figure 2 ,in, Figure 2 for Figure 1 In the enlarged schematic diagram at P in the middle, the aperture 3 is arranged on the surface of the super lens 1 close to the image side, that is, the aperture 3 is arranged on the rear surface of the super lens 1.

[0079] In some embodiments, the aperture 3 is disposed between the superlens 1 and the aspheric lens 2 , that is, there is a preset distance between the aperture 3 and the superlens 1 , and there is also a certain distance between the aperture 3 and the aspheric lens 2 .

[0080] The far-infrared optical system 100 provided by the present application has the following benefits:

[0081] (1) The total optical length is less than 18 mm.

[0082] (2) The F number is less than 1.2.

[0083] (3) At a spatial frequency of 42 lp / mm, the MTF (Modulation Transfer Function) value at the maximum field of view is greater than 0.2.

[0084] The present application exemplarily provides three far-infrared optical systems 100 that meet usage requirements in three embodiments. Next, the far-infrared optical systems 100 provided by the various embodiments of the present application are introduced in detail.

[0085] Example 1

[0086] Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 1. Figure 1 The mid-infrared optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, a super lens 1, an aperture 3, an aspheric lens 2, and a protective member 4, wherein the aperture 3 is disposed on the surface of the super lens 1 close to the image side, the protective member 4 is a protective glass, and the micro-nano structure 12 is disposed on the surface of the substrate 11 close to the image side. Some parameters of the far-infrared optical system 100 provided in Example 1 are shown in Table 1-1.

[0087] Table 1-1. Partial parameters of the far-infrared optical system 100 provided in Example 1

[0088] parameter data Total optical length (TTL) 15mm Maximum field of view (2ω) 37.4° F-number 1.1 Effective focal length 5.78mm Working band Far infrared (8um-12um)

[0089] As can be seen from Table 1-1, the working band of the far-infrared optical system 100 is 8um-12um, the total optical length of the far-infrared optical system 100 is 15mm, the maximum field angle of the far-infrared optical system 100 is 37.4°, and the effective focal length of the far-infrared optical system 100 is 5.78mm. The F number of the far-infrared optical system 100 is 1.1, which can greatly increase the amount of light entering the far-infrared optical system 100, and collect as much energy as possible entering the far-infrared optical system 100 when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.

[0090] Starting from the surface close to the object side of the metalens 1, along the optical axis S from the object plane A to the image plane B, each surface in the far-infrared optical system 100 is numbered, and the parameters of each surface are summarized to obtain the following Table 1-2.

[0091] Table 1-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 1

[0092]

[0093]

[0094] For each surface in Table 1-2, surface 1 is the surface of the superlens 1 close to the object side, and surface 2 is the surface of the superlens 1 close to the image side. Since the micro-nano structure 12 is provided on surface 2, and the aperture 3 is located on surface 2, surface 2 is recorded as the structure surface-aperture. Surface 3 is the surface of the aspheric lens 2 close to the object side, and surface 4 is the surface of the aspheric lens 2 close to the image side. Surface 5 is the surface of the protective member 4 close to the object side, and surface 6 is the surface of the protective member 4 close to the image side. Surface 7 is the image surface B.

[0095] As can be seen from Table 1-2, the radius of curvature of surface 1 is infinite, that is, surface 1 is a plane, the distance between surface 1 and surface 2 is 0.3 mm, and the material between surface 1 and surface 2 is silicon. The radius of curvature of surface 2 is infinite, that is, surface 2 is a plane, the distance between surface 2 and surface 3 is 0.59 mm, and the material between surface 2 and surface 3 is air. The radius of curvature of surface 3 is -11.2 mm, the distance between surface 3 and surface 4 is 6.03 mm, and the material between surface 3 and surface 4 is chalcogenide glass, specifically, the material between surface 3 and surface 4 is IRG206. The radius of curvature of surface 4 is -7.4 mm, the distance between surface 4 and surface 5 is 7.28 mm, and the material between surface 4 and surface 5 is air. The radius of curvature of surface 5 is infinite, that is, surface 5 is a plane, the distance between surface 5 and surface 6 is 0.7 mm, and the material between surface 5 and surface 6 is silicon. The curvature radius of surface 6 is infinite, that is, surface 6 is a plane, the distance between surface 6 and surface 7 is 0.1 mm, and the material between surface 6 and surface 7 is air.

[0096] Surface 3 and surface 4 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0097]

[0098] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis S direction; c is the curvature of the aspherical surface, c = 1 / R, R is the curvature radius of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 3 and surface 4 can be obtained from Table 1-3.

[0099] Table 1-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 1

[0100]

[0101] Please refer to Table 1-3. For surface 3, K is 1.4E+01, A is 2.9E-03, B is -2.2E-03, C is 5.4E-04, D is -4.2E-05, E is -8.3E-06, F is 1.9E-06, and G is -1.1E-07. The coefficients of the even-order aspheric surface of surface 4 are not described one by one again.

[0102] See also Figure 3 , Figure 3 FIG. 1 shows the MTF field curve of the far-infrared optical system 100 provided in Example 1. Figure 3 The horizontal axis in is the X-axis field of view angle, and its unit is degree. Figure 3 The vertical axis is the MTF value. Figure 3 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal image curve S2 and the meridional image curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal image curve S3 and the meridional image curve T3 of the field of view. Figure 3 It can be seen that at a spatial frequency of 42lp / mm, within the full field of view, the MTF is greater than 0.2, and within the 0.8 field of view (14.96°), the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0103] See also Figure 4 , Figure 4 1 shows a field curvature diagram of the far-infrared optical system 100 provided in Example 1, Figure 4 The horizontal axis is the field curvature, and its unit is millimeters. Figure 4 The vertical axis is the field of view angle, and its unit is degree. Figure 4 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 9 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 9 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S4 is the field curvature of far-infrared light with a wavelength of 11 microns in the sagittal direction, and T4 is the field curvature of far-infrared light with a wavelength of 11 microns in the meridional direction; S5 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T5 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Figure 4 It can be seen that the maximum field curvature of the far-infrared optical system 100 in the sagittal direction is 0.0350 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction is 0.0669 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0104] See also Figure 5 , Figure 51 shows a distortion diagram of the far-infrared optical system 100 provided in Example 1, wherein: Figure 5 The distortion of far-infrared light with wavelengths of 8 microns, 9 microns, 10 microns, 11 microns and 12 microns is shown in FIG. Figure 5 The five curves in the figure almost completely overlap, so the five curves are not distinguished here. Figure 5 It can be seen that the maximum distortion of the far-infrared optical system 100 provided in Example 1 is 4.8%, which meets the distortion requirement of the excellent imaging quality standard.

[0105] See also Figure 6 , Figure 6 The vertical axis chromatic aberration diagram of the far-infrared optical system 100 provided in Example 1 under far-infrared light with wavelengths of 8 microns, 9 microns, 10 microns, 11 microns and 12 microns is shown, Figure 6 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane B, in microns. Figure 6 The vertical axis is the field of view angle, and its unit is degree. Figure 6 8 micrometers of far infrared light M1, 9 micrometers of far infrared light M2, 10 micrometers of far infrared light M3, 11 micrometers of far infrared light M3, and 12 micrometers of far infrared light M3 are shown in FIG. 1 , wherein the curve at the horizontal axis 0 represents the far infrared light M3 with a wavelength of 10 micrometers. Figure 6 It can be seen that within the full field of view, the maximum vertical axis chromatic aberration of the far-infrared optical system 100 is about 4.2 microns, the chromatic aberration is small, and the dispersion is not obvious.

[0106] Example 2

[0107] Figure 7 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 2. Figure 7 The mid-to-far infrared optical system 100 includes, along the optical axis S, from the object plane A to the image plane B, a super lens 1, an aperture 3, an aspheric lens 2, and a protective member 4, wherein the aperture 3 is disposed on the surface of the super lens 1 close to the image side, the protective member 4 is a protective glass, and the micro-nano structure 12 is disposed on the surface of the substrate 11 close to the image side. Some parameters of the far-infrared optical system 100 provided in Example 2 are shown in Table 2-1.

[0108] Table 2-1. Partial parameters of the far-infrared optical system 100 provided in Example 2

[0109] parameter data Total optical length (TTL) 15mm Maximum field of view (2ω) 37.4° F-number 1.1 Effective focal length 5.79mm Working band Far infrared (8um-12um)

[0110] As can be seen from Table 2-1, the working band of the far-infrared optical system 100 is 8um-12um, the total optical length of the far-infrared optical system 100 is 15mm, the maximum field angle of the far-infrared optical system 100 is 37.4°, and the effective focal length of the far-infrared optical system 100 is 5.79mm. The F number of the far-infrared optical system 100 is 1.1, which can greatly increase the amount of light entering the far-infrared optical system 100, and collect as much energy as possible entering the far-infrared optical system 100 when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.

[0111] Starting from the surface close to the object side of the metalens 1, along the optical axis S from the object plane A to the image plane B, the surfaces in the far-infrared optical system 100 are numbered, and the parameters of each surface are summarized to obtain the following Table 2-2.

[0112] Table 2-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 2

[0113]

[0114]

[0115] The analysis of each surface in Table 2-2 can refer to Example 1, and no further analysis is performed in this example.

[0116] Surface 3 and surface 4 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0117]

[0118] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis S; c is the curvature of the aspherical surface, c = 1 / R, R is the radius of curvature of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 3 and surface 4 can be obtained from Table 2-3.

[0119] Table 2-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 2

[0120]

[0121] The method for querying the coefficients of each order of the even-order aspheric surfaces of surface 3 and surface 4 can refer to embodiment 1, which will not be repeated here.

[0122] See also Figure 8 , Figure 8 FIG. 2 shows the MTF field curve of the far-infrared optical system 100 provided in Example 2. Figure 8The horizontal axis in is the X-axis field of view angle, and its unit is degree. Figure 8 The vertical axis is the MTF value. Figure 8 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal image curve S2 and the meridional image curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal image curve S3 and the meridional image curve T3 of the field of view. Figure 8 It can be seen that at a spatial frequency of 42lp / mm, within the full field of view, the MTF is greater than 0.28, and within the 0.9 field of view (16.83°), the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0123] See also Fig. 9 , Fig. 9 2 shows a field curvature diagram of the far-infrared optical system 100 provided in Example 2. Fig. 9 The horizontal axis is the field curvature, and its unit is millimeters. Fig. 9 The vertical axis is the field of view angle, and its unit is degree. Fig. 9 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 9 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 9 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S4 is the field curvature of far-infrared light with a wavelength of 11 microns in the sagittal direction, and T4 is the field curvature of far-infrared light with a wavelength of 11 microns in the meridional direction; S5 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T5 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Fig. 9 It can be seen that the maximum field curvature of the far-infrared optical system 100 in the sagittal direction is 0.0378 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction is 0.0361 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0124] See also Fig.10 , Fig.10 1 shows a distortion diagram of the far-infrared optical system 100 provided in Example 2, wherein: Fig.10 The distortion of far-infrared light with wavelengths of 8 microns, 9 microns, 10 microns, 11 microns and 12 microns is shown in FIG. Fig.10 The five curves in the figure almost completely overlap, so the five curves are not distinguished here. Fig.10 It can be seen that the maximum distortion of the far-infrared optical system 100 provided in Example 2 is -5%, which meets the distortion requirement of the excellent imaging quality standard.

[0125] See also Fig.11, Fig.11 The vertical axis chromatic aberration diagram of the far-infrared optical system 100 provided in Example 2 under far-infrared light with wavelengths of 8 microns, 9 microns, 10 microns, 11 microns and 12 microns is shown, Fig.11 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane B, in microns. Fig.11 The vertical axis is the field of view angle, and its unit is degree. Fig.11 8 micrometers of far infrared light M1, 9 micrometers of far infrared light M2, 10 micrometers of far infrared light M3, 11 micrometers of far infrared light M3, and 12 micrometers of far infrared light M3 are shown in FIG. 1 , wherein the curve at the horizontal axis 0 represents the far infrared light M3 with a wavelength of 10 micrometers. Fig.11 It can be seen that within the full field of view, the maximum vertical axis chromatic aberration of the far-infrared optical system 100 is about 7 microns, the chromatic aberration is small, and the dispersion is not obvious.

[0126] Example 3

[0127] Fig.12 FIG. 1 shows a schematic diagram of the architecture layout of the far-infrared optical system 100 provided in Example 3. Fig.12 The mid-to-far infrared optical system 100 includes, in sequence along the optical axis S from the object plane A to the image plane B: a superlens 1, an aperture 3, an aspheric lens 2, and a protective member 4, wherein the aperture 3 is arranged on the surface of the superlens 1 close to the image side, the protective member 4 is a protective glass, and the micro-nano structure 12 is arranged on the surface of the substrate 11 close to the image side.

[0128] Some parameters of the far-infrared optical system 100 provided in Example 3 are shown in Table 3-1.

[0129] Table 3-1. Partial parameters of the far-infrared optical system 100 provided in Example 3

[0130] parameter data Total optical length (TTL) 15mm Maximum field of view (2ω) 37.4° F-number 1.1 Effective focal length 5.89mm Working band Far infrared (8um-12um)

[0131] As can be seen from Table 3-1, the working band of the far-infrared optical system 100 is 8um-12um, the total optical length of the far-infrared optical system 100 is 15mm, the maximum field angle of the far-infrared optical system 100 is 37.4°, and the effective focal length of the far-infrared optical system 100 is 5.89mm. The F number of the far-infrared optical system 100 is 1.1, which can greatly increase the amount of light entering the far-infrared optical system 100, and collect as much energy as possible entering the far-infrared optical system 100 when the image sensor has a low response to light energy, thereby ensuring excellent imaging quality.

[0132] Starting from the surface close to the object side of the metalens 1, along the optical axis S from the object plane A to the image plane B, the surfaces in the far-infrared optical system 100 are numbered, and the parameters of each surface are summarized to obtain the following Table 3-2.

[0133] Table 3-2. Parameters of various surfaces in the far-infrared optical system 100 provided in Example 3

[0134] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Spherical unlimited 0.3 silicon 2 Structural surface-aperture unlimited 0.62 - 3 Aspheric -11.4 6.12 IRG206 4 Aspheric -7.6 7.16 - 5 Spherical unlimited 0.7 silicon 6 Spherical unlimited 0.1 - 7 Spherical unlimited - -

[0135] The analysis of each surface in Table 3-2 can refer to Example 1, and no further analysis is performed in this example.

[0136] Surface 3 and surface 4 are even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0137]

[0138] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis S; c is the curvature of the aspherical surface, c = 1 / R, R is the radius of curvature of the aspherical surface; k is the cone coefficient; A, B, C, D... are the aspherical coefficients. The values ​​of k, A, B, C, D... of surface 3 and surface 4 can be obtained from Table 3-3.

[0139] Table 3-3. Coefficients of the even-order aspheric surfaces in the far-infrared optical system 100 provided in Example 3

[0140]

[0141] The method for querying the coefficients of the even-order aspheric surfaces of surface 3 and surface 4 can refer to embodiment 1, which will not be repeated here.

[0142] See also Fig.13 , Fig.13 The MTF (Modulation Transfer Function, MTF for short) field of view curve of the far-infrared optical system 100 provided in Example 3 is shown. Fig.13 The horizontal axis in is the X-axis field of view angle, and its unit is degree. Fig.13 The vertical axis is the MTF value. Fig.13 The MTF of 10lp / mm spatial frequency is listed as the sagittal curve S1 and the meridional curve T1 of the field of view, the MTF of 21lp / mm spatial frequency is listed as the sagittal image curve S2 and the meridional image curve T2 of the field of view, and the MTF of 42lp / mm spatial frequency is listed as the sagittal image curve S3 and the meridional image curve T3 of the field of view. Fig.13It can be seen that at a spatial frequency of 42lp / mm, within the full field of view, the MTF is greater than 0.2, and within the 0.8 field of view (14.96°), the MTF is greater than 0.3, and the imaging quality of the far-infrared optical system 100 is relatively good.

[0143] See also Fig.14 , Fig.14 1 shows a field curvature diagram of the far-infrared optical system 100 provided in Example 3, Fig.14 The horizontal axis is the field curvature, and its unit is millimeters. Fig.14 The vertical axis is the field of view angle, and its unit is degree. Fig.14 S1 is the field curvature of far-infrared light with a wavelength of 8 microns in the sagittal direction, and T1 is the field curvature of far-infrared light with a wavelength of 8 microns in the meridional direction; S2 is the field curvature of far-infrared light with a wavelength of 9 microns in the sagittal direction, and T2 is the field curvature of far-infrared light with a wavelength of 9 microns in the meridional direction; S3 is the field curvature of far-infrared light with a wavelength of 10 microns in the sagittal direction, and T3 is the field curvature of far-infrared light with a wavelength of 10 microns in the meridional direction; S4 is the field curvature of far-infrared light with a wavelength of 11 microns in the sagittal direction, and T4 is the field curvature of far-infrared light with a wavelength of 11 microns in the meridional direction; S5 is the field curvature of far-infrared light with a wavelength of 12 microns in the sagittal direction, and T5 is the field curvature of far-infrared light with a wavelength of 12 microns in the meridional direction. Fig.14 It can be seen that the maximum field curvature of the far-infrared optical system 100 in the sagittal direction is 0.0680 mm, and the maximum field curvature of the far-infrared optical system 100 in the meridional direction is 0.1603 mm, which meets the requirements for field curvature in the excellent imaging quality standard.

[0144] See also Fig.15 , Fig.15 : shows a distortion diagram of the far-infrared optical system 100 provided in Example 3, wherein: Fig.15 The distortion of far-infrared light with wavelengths of 8 microns, 9 microns, 10 microns, 11 microns and 12 microns is shown in FIG. Fig.15 The five curves in the figure almost completely overlap, so the five curves are not distinguished here. Fig.15 It can be seen that the maximum distortion of the far-infrared optical system 100 provided in Example 3 is -4.3%, which meets the distortion requirement of the excellent imaging quality standard.

[0145] See also Fig.16 , Fig.16 The vertical axis chromatic aberration diagram of the far-infrared optical system 100 provided in Example 3 under far-infrared light with wavelengths of 8 microns, 9 microns, 10 microns, 11 microns and 12 microns is shown, Fig.16 The horizontal axis is the position of light of different wavelengths on the vertical axis image plane B, in microns. Fig.16 The vertical axis is the field of view angle, and its unit is degree. Fig.168 micrometers of far infrared light M1, 9 micrometers of far infrared light M2, 10 micrometers of far infrared light M3, 11 micrometers of far infrared light M3, and 12 micrometers of far infrared light M3 are shown in FIG. 1 , wherein the curve at the horizontal axis 0 represents the far infrared light M3 with a wavelength of 10 micrometers. Fig.16 It can be seen that within the full field of view, the maximum vertical axis chromatic aberration of the far-infrared optical system 100 is about 4.1 microns, the chromatic aberration is small, and the dispersion is not obvious.

[0146] After summarizing the parameters of the far-infrared optical system 100 provided by the above three embodiments, the following Table 4 is obtained. Table 4 is mainly used to illustrate that the conditions satisfied by the far-infrared optical system 100 provided by the present application are all verified and supported by experiments.

[0147] Table 4. Parameters of the far-infrared optical system 100 provided in various embodiments

[0148]

[0149] The present application also provides a far-infrared optical lens (not shown), which includes an imaging detector (not shown) and the above-mentioned far-infrared optical system 100. The imaging detector is arranged on the image plane B of the far-infrared optical system 100, and the imaging detector includes but is not limited to CMOS (Complementary Metal Oxide Semiconductor, referred to as CMOS, complementary metal oxide semiconductor) and CCD (Charge Coupled Device, referred to as CCD, charge coupled device).

[0150] Those skilled in the art will readily appreciate other embodiments of the present application after considering the specification and practicing the utility model disclosed herein. The present application is intended to cover any modification, use or adaptation of the present application, which follows the general principles of the present application and includes common knowledge or customary techniques in the art that are not disclosed in the present application. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present application are indicated by the appended claims.

Claims

1. A far-infrared optical system, characterized in that: The far-infrared optical system comprises, in order from the object side to the image side along the optical axis: a super lens and an aspheric lens, wherein the optical focal length of the super lens is positive; the optical focal length of the aspheric lens is positive, the surface of the aspheric lens close to the object side is convex to the image side, and the surface of the aspheric lens close to the image side is convex to the image side; Wherein, the far-infrared optical system satisfies: Wherein Φ2 is the focal length of the aspheric lens, and Φ m is the optical power of the metalens.

2. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the f m is the focal length of the superlens, and f is the effective focal length of the far-infrared optical system.

3. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, Δλ is the maximum wavelength difference of the working band of the far-infrared optical system, is the phase of the superlens, and x is the distance between any point on the superlens and the center of the superlens.

4. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, T2 is the center thickness of the aspheric lens, R1 is the curvature radius of the surface of the aspheric lens close to the object side, K1 is the cone coefficient of the surface of the aspheric lens close to the object side, R2 is the curvature radius of the surface of the aspheric lens close to the image side, and K2 is the cone coefficient of the surface of the aspheric lens close to the image side.

5. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, n is the refractive index of the material of the aspheric lens, the EPD is the entrance pupil diameter of the far-infrared optical system, R2 is the curvature radius of the surface of the aspheric lens close to the image side, and K2 is the cone coefficient of the surface of the aspheric lens close to the image side.

6. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the T m is the center thickness of the super lens, T2 is the center thickness of the aspheric lens, and T m2 is the thickness of the air gap between the superlens and the aspheric lens on the optical axis.

7. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, f2 is the focal length of the aspheric lens, and T2 is the thickness of the aspheric lens on the optical axis.

8. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Wherein, R1 is the curvature radius of the surface of the aspheric lens close to the object side, and R2 is the curvature radius of the surface of the aspheric lens close to the image side.

9. The far-infrared optical system according to claim 1, characterized in that: The far-infrared optical system meets the following requirements: Among them, the F# is the aperture number of the far-infrared optical system, and the FOV is the maximum field of view angle of the far-infrared optical system.

10. The far-infrared optical system according to any one of claims 1 to 9, characterized in that: The far-infrared optical system further includes an aperture, which is located between the super lens and the aspherical lens; or, the aperture is located on a side of the super lens away from an image plane of the far-infrared optical system.

11. The far-infrared optical system according to claim 10, characterized in that: The aperture is provided on a surface of the super lens close to the image side.

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

Images