Infrared optical system and infrared optical lens

Abstract

The utility model provides an infrared optical system and an infrared optical lens. The infrared optical system comprises a super lens and a refraction lens which are sequentially arranged from an object side to an image side along an optical axis; the super lens comprises a substrate and a micro-nano structure located on the surface of the substrate, and the micro-nano structure is arranged on at least one of the image side face and the object side face of the substrate. The object side surface and the image side surface of the refraction lens protrude towards the image side; the infrared optical system satisfies the following conditions: # imgabs0 # L1 is the distance between the object side surface of the super lens and the image side surface of the refraction lens on the optical axis, and L2 is the thickness of the air gap between the super lens and the refraction lens on the optical axis. And the value of # imgabs 1 # is controlled between 3.2 and 5.8, so that the size of the infrared optical system can be controlled on the premise of ensuring the imaging quality of the infrared optical system, and the infrared optical system can meet the requirement of miniaturization. The infrared optical system adopts the combination of the super lens and the refraction lens, so that the size of the infrared optical system is obviously reduced on the premise of meeting the imaging requirement, and the production cost is reduced.

Description

Technical Field

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

[0002] Far infrared lenses can make up for the defects of visible light imaging lenses. They can replace visible light imaging in fog, haze, rain, snow, and night, and are widely used in security, vehicle-mounted, military and other fields. Infrared optical systems in the prior art are usually composed of traditional refractive lenses. Since the refractive lens itself has a large thickness, there is usually a preset distance between two adjacent refractive lenses. Considering the processability, the optical system is large in size and does not have an advantage in size and cost. Utility Model Content

[0003] In view of the above technical problems, the embodiments of the present application provide an infrared optical system and an infrared optical lens to solve the problem of large volume of the infrared optical system in the prior art.

[0004] A first aspect of an embodiment of the present application provides an infrared optical system, the infrared optical system comprising a super lens and a refractive lens sequentially arranged from an object side to an image side along an optical axis of the infrared optical system; wherein the super lens comprises a substrate and a micro-nano structure located on a surface of the substrate, the micro-nano structure being arranged on at least one of an image side surface of the substrate and an object side surface of the substrate; the object side surface of the refractive lens is convex toward the image side, and the image side surface of the refractive lens is convex toward the image side;

[0005] The infrared optical system meets the following requirements:

[0006]

[0007] Wherein, L1 is the distance between the object side surface of the super lens and the image side surface of the refractive lens on the optical axis, and L2 is the thickness of the air gap between the super lens and the refractive lens on the optical axis.

[0008] Optionally, the refractive lens is a spherical lens or an aspherical lens.

[0009] Optionally, the infrared optical system satisfies:

[0010]

[0011] Where f is the effective focal length of the infrared optical system, f m is the focal length of the metalens.

[0012] Optionally, the infrared optical system satisfies:

[0013] 45D≤ΔΦ m≤100D

[0014] Among them, ΔΦ m is the difference between the maximum and minimum optical focal length of the metalens in the working band.

[0015] Optionally, the infrared optical system satisfies:

[0016]

[0017] Among them, T m is the center thickness of the metalens, T a is the center thickness of the refractive lens, Φ m is the focal length provided by the metalens at the central wavelength, Φ a It is the optical power provided by the refractive lens at the central wavelength.

[0018] Optionally, the infrared optical system satisfies:

[0019]

[0020] Where p represents a radian of 2π, is the maximum phase difference provided by the metalens, r m is the effective area radius of the superlens.

[0021] Optionally, the infrared optical system satisfies:

[0022]

[0023] in, is the maximum spatial phase gradient of the metalens, is the minimum spatial phase gradient of the metalens.

[0024] Optionally, the infrared optical system satisfies:

[0025]

[0026] Among them, f m is the focal length of the metalens, D m is the effective area diameter of the metalens, and F# is the aperture number of the infrared optical system.

[0027] Optionally, the infrared optical system satisfies:

[0028]

[0029] Wherein, f is the effective focal length of the infrared optical system, BFL is the optical back focal length of the infrared optical system, TTL is the total optical length of the infrared optical system, and ImgH is the imaging area radius of the infrared optical system on the image plane corresponding to the maximum half field of view angle.

[0030] Optionally, the infrared optical system satisfies:

[0031]

[0032] Wherein, ΔT is the applicable operating temperature range of the infrared optical system, FOV is the field of view angle of the infrared optical system, and EPD is the entrance pupil diameter of the infrared optical system.

[0033] Optionally, the infrared optical system satisfies:

[0034]

[0035] Among them, Φ m is the focal length of the metalens at the central wavelength, TTL is the total optical length of the infrared optical system, the surface with the larger maximum curvature between the object side of the refractive lens and the image side of the refractive lens is the target surface, θ b It is the angle between the tangent line at the maximum mechanical diameter of the target surface with curvature and the optical axis.

[0036] Optionally, the infrared optical system satisfies:

[0037]

[0038] Among them, R1 is the curvature radius of the object side of the refractive lens, R2 is the curvature radius of the image side of the refractive lens, BFL is the optical back focal length of the infrared optical system, and L2 is the distance between the object side of the refractive lens and the image side of the metalens on the optical axis.

[0039] Optionally, the infrared optical system satisfies:

[0040]

[0041] Among them, T m is the center thickness of the metalens, D m is the maximum mechanical diameter of the metalens, T a is the center thickness of the refractive lens, D a is the maximum mechanical diameter of the refractive lens.

[0042] Optionally, the infrared optical system also includes an aperture, which is arranged on the object side of the superlens; or, the aperture is arranged on the object side of the superlens; or, the aperture is arranged on the image side of the superlens; or, the aperture is arranged on the object side of the refractive lens; or, the aperture is arranged between the superlens and the refractive lens.

[0043] Another aspect of an embodiment of the present application provides an infrared optical lens, including an imaging detector and an infrared optical system, wherein the imaging detector is arranged on an image plane of the infrared optical system.

[0044] In the present application, the infrared optical system includes a metalens and a refractive lens arranged in sequence from the object side to the image side along the optical axis; wherein the metalens includes a substrate and a micro-nano structure located on the surface of the substrate, and the micro-nano structure is arranged on at least one of the image side surface of the substrate and the object side surface of the substrate; the object side surface of the refractive lens is convex to the image side, and the image side surface of the refractive lens is convex to the image side; the infrared optical system satisfies: Wherein, L1 is the distance between the object side of the metalens and the image side of the refractive lens on the optical axis, and L2 is the thickness of the air gap between the metalens and the refractive lens on the optical axis. The value of is controlled between 3.2 and 5.8, which is conducive to controlling the volume of the infrared optical system while ensuring the imaging quality of the infrared optical system, so that the infrared optical system can meet the needs of miniaturization. The infrared optical system adopts a combination of super lens and refractive lens, which significantly reduces the volume of the infrared optical system and reduces the production cost while meeting the imaging requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown;

[0047] Figure 2 The MTF field of view curve diagram of the infrared optical system in one embodiment of the present application is shown;

[0048] Figure 3 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown;

[0049] Figure 4 The MTF field of view curve diagram of the infrared optical system in one embodiment of the present application is shown;

[0050] Figure 5 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown;

[0051] Figure 6 The MTF field of view curve diagram of the infrared optical system in one embodiment of the present application is shown;

[0052] Figure 7 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown;

[0053] Figure 8The MTF field of view curve diagram of the infrared optical system in one embodiment of the present application is shown;

[0054] Fig. 9 A schematic diagram of the architecture layout of an infrared optical system in an embodiment of the present application is shown;

[0055] Fig.10 The MTF field of view curve diagram of the infrared optical system in one embodiment of the present application is shown.

[0056] List of reference numerals:

[0057] 10-first refractive lens, 20-super lens, 30-second refractive lens, 40-aperture, 50-protective glass, 90-optical axis. DETAILED DESCRIPTION

[0058] The present application will now be described more fully below with reference to the accompanying drawings, in which various embodiments are shown. However, the present application can be implemented in many different ways and should not be construed as being limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that the present application will be exhaustive and complete, and will fully convey the scope of the present application to those skilled in the art. The same reference numerals throughout the text represent the same components. Furthermore, in the accompanying drawings, the thickness, ratios, and sizes of the components are exaggerated for clarity.

[0059] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to be limiting. Unless the context clearly indicates otherwise, "one", "the", "at least one" as used herein do not represent a limitation on quantity, but are intended to include both the singular and the plural. For example, unless the context clearly indicates otherwise, "a component" has the same meaning as "at least one component". "At least one" should not be interpreted as being limited to the number "one". "Or" means "and / or". The term "and / or" includes any and all combinations of one or more of the associated listed items.

[0060] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art. Terms defined in commonly used dictionaries should be interpreted as having the same meanings as in the relevant technical context, and unless clearly defined in the specification, these terms are not interpreted as having formal meanings in an idealized or overly formal sense.

[0061] The meaning of “include” or “comprising” specifies properties, quantities, steps, operations, components or a combination thereof, but does not exclude other properties, quantities, steps, operations, components or a combination thereof.

[0062] Embodiments are described herein with reference to cross-sectional views as idealized embodiments. Thus, variations in shape relative to the illustrated diagram are anticipated as a result of, for example, manufacturing techniques and / or tolerances. Therefore, the embodiments described herein should not be interpreted as being limited to the specific shapes of the regions as shown herein, but should include deviations in shape due to, for example, manufacturing. For example, a region shown or described as flat may typically have rough and / or nonlinear features. Moreover, the sharp angles shown may be rounded. Therefore, the regions shown in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the claims.

[0063] The present application provides an infrared optical system. The infrared optical system and infrared optical lens in the related art are usually composed of traditional refractive lenses. They are usually large in size and have many lenses, which are not advantageous in terms of size and cost. This feature of the related art does not meet the current demand for miniaturization and lightweight of optical devices.

[0064] Hereinafter, exemplary embodiments according to the present application will be described with reference to the accompanying drawings.

[0065] Figure 1 Schematic diagram of the architecture layout of an infrared optical system provided by an embodiment of the present application is shown, wherein from left to right is the direction from the object side to the image side. Figure 1 The infrared optical system provided in the embodiment of the present application includes a super lens 10 and a refractive lens 20, and the super lens 10 and the refractive lens 20 are arranged in sequence from the object side to the image side along the optical axis 90.

[0066] The object-side surface of the refractive lens 20 is convex toward the image side, and the image-side surface of the refractive lens 20 is convex toward the image side.

[0067] The superlens 10 includes a substrate 11 and a micro-nano structure 12, wherein the micro-nano structure 12 is disposed on at least one of the object side surface of the substrate 11 and the image side surface of the substrate 11. According to the phase modulation method adopted, the corresponding phase modulation formula can be adaptively used to configure various parameters of the micro-nano structure 12, so that the superlens 10 can achieve corresponding optical performance.

[0068] The superlens 10 can provide different focal lengths at different wavelengths. Therefore, the superlens 10 cooperates with the refractive lens 20 to converge the focus of each single wavelength light at the same position, and has the function of correcting the chromatic aberration of the infrared optical system.

[0069] The infrared optical system meets the following conditions:

[0070]

[0071] Wherein, L1 is the distance between the object side surface of the super lens 10 and the image side surface of the refractive lens 20 on the optical axis 90, and L2 is the thickness of the air gap between the super lens 10 and the refractive lens 20 on the optical axis 90. L1 and L2 have the same dimension, both of which are length units, such as millimeters. The value of reflects the air occupancy in the infrared optical system. The upper limit of reflects the minimum thickness of the air gap between the metalens 10 and the refractive lens 20. The lower limit of reflects the maximum thickness of the air gap between the metalens 10 and the refractive lens 20. The value is controlled between 3.2 and 5.8, which is beneficial to controlling the volume of the infrared optical system while ensuring the imaging quality of the infrared optical system, so that the infrared optical system can meet the demand of miniaturization.

[0072] In the present application, the superlens 10 can play the role of achromatism in the infrared optical system. At the same time, the superlens 10 provides optical power while correcting chromatic aberration. The superlens 10 providing optical power and the refractive lens 20 providing optical power correct aberration together. The infrared optical system proposed in the present application adopts a combination of the superlens 10 and the refractive lens 20, which significantly reduces the volume of the infrared optical system and reduces the production cost while meeting the imaging requirements.

[0073] In some embodiments, the refractive lens 20 is a spherical lens, which can further reduce the production cost of the infrared optical system.

[0074] In some embodiments, the refractive lens 20 is an aspherical lens, which can improve the imaging quality of the infrared optical system.

[0075] In the embodiment of the present application and various optional embodiments, the aspheric lens is an even-order aspheric lens, and its surface shape satisfies the following conditions:

[0076]

[0077] Among them, Z(r) is the distance vector height from the vertex of the aspheric lens when the aspheric lens is at a height of r in a direction parallel to the optical axis 90, c=1 / R, R is the radius of curvature of the aspheric surface; k is the cone coefficient, and A, B, C, and D are the aspheric coefficients respectively.

[0078] In an optional embodiment, the micro-nano structure 12 is only disposed on the object-side surface of the substrate 11 .

[0079] In an optional embodiment, the micro-nano structure 12 is only disposed on the image side of the substrate 11 .

[0080] In an optional embodiment, the object-side surface of the substrate 11 and the image-side surface of the substrate 11 are both provided with micro-nano structures 12 .

[0081] In an optional embodiment, the micro-nano structure 12 is a positive micro-nano structure.

[0082] In an optional embodiment, the micro-nano structure 12 is a negative micro-nano structure.

[0083] In an optional embodiment, the micro-nano structure 12 is provided with a layer to make the processing technology of the superlens 10 compatible with the existing semiconductor processing technology, which can facilitate the production of the superlens 10.

[0084] In an optional embodiment, the micro-nano structure 12 is provided with two or more layers, so that the superlens 10 has a larger optical focal length that meets the expected requirements.

[0085] The position of the micro-nano structure 12 on the substrate 11, the positive and negative sides 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 10 has the expected performance.

[0086] In a specific embodiment, the specific structure of the metalens 10 is: a layer of micro-nano structure 12 is disposed on both the object side and the image side of the substrate 11, and the micro-nano structure 12 is a negative micro-nano structure. It should be noted that this is only an exemplary description and cannot be understood as a limitation on the metalens 10.

[0087] In an optional embodiment, the infrared optical system satisfies the following conditional formula:

[0088]

[0089] Wherein, TTL (Total Track Length, abbreviated as TTL) is the total optical length of the infrared optical system. In the present application, TTL is the distance from the object side of the metalens 10 to the image plane of the infrared optical system on the optical axis 90, and L1 is the distance between the object side of the metalens 10 and the image side of the refractive lens 20 on the optical axis 90. L1 and TTL have the same dimension, both of which are length units, such as mm.

[0090] The length of L1 directly affects the mechanical length of the infrared optical lens corresponding to the infrared optical system. Therefore, the upper limit of L1 / TTL reflects the maximum proportion of the infrared optical lens corresponding to the infrared optical system in the optical path; the lower limit of L1 / TTL represents the minimum proportion of the infrared optical lens corresponding to the infrared optical system in the optical path, reflecting the limit of the compressed lens length. The maximum value of L1 / TTL is less than 0.60, which can make the volume of the infrared optical lens corresponding to the infrared optical system relatively small.

[0091] In an optional embodiment, the infrared optical system also satisfies the following conditional formula:

[0092]

[0093] Where f is the effective focal length of the infrared optical system, f m is the focal length of the superlens 10. When the superlens 10 is a double-sided superlens, f is selected m Specifically, when the metalens 10 is a double-sided metalens, both the image side surface of the metalens 10 and the object side surface of the metalens 10 are provided with a micro-nano structure 12. If the focal length provided by the image side surface of the metalens 10 is greater than the focal length provided by the object side surface of the metalens 10, then f m is the focal length provided by the image side of the metalens 10. f and f m The dimensions of are the same, both are length units, such as mm. m The value of / f reflects the focal length proportion of the superlens 10 in the infrared optical system. m The upper limit of / f represents the minimum light focusing ability that the metalens 10 needs to provide in the infrared optical system, f m The lower limit of / f represents the maximum light focusing ability that the metalens 10 needs to provide in the infrared optical system.

[0094] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0095] 45D≤ΔΦ m ≤100D

[0096] Super Lens 10 Optical Power Φ m will change with the change of the wavelength of the light beam. When the superlens 10 has a larger focal power Φ m When ΔΦ is ΔΦ, the super lens 10 can provide a stronger light converging capability. m is the maximum optical power Φ of the metalens 10 in the working band max With the minimum value Φ min The difference, ΔΦ m The unit is D, which is equal to m -1 . ΔΦ m The value reflects the ability of the metalens 10 to correct chromatic aberration, ΔΦ m The lower limit of represents the minimum chromatic aberration correction capability that the metalens 10 can provide in the infrared optical system, ΔΦ m The upper limit represents the maximum chromatic aberration correction capability that the metalens 10 can provide in the infrared optical system.

[0097] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0098]

[0099] Among them, T m is the center thickness of the superlens 10, i.e., Tm T is the thickness of the metalens 10 on the optical axis 90. a is the center thickness of the refractive lens 20, that is, T a is the thickness of the refractive lens 20 on the optical axis 90. Φ m is the focal length provided by the metalens 10 at the central wavelength, Φ a is the focal length provided by the refractive lens 20 at the central wavelength, T m and T a have the same dimension, both are length units, such as mm, Φ m and Φ a The dimensions are the same, both are D, D is equal to m -1 Φ m / T m -Φ a / T a The difference between the ratio of the optical power of the metalens 10 to the central thickness and the ratio of the optical power of the refractive lens 20 to the central thickness reflects the thickness advantage of the metalens 10 over the refractive lens 20 in the infrared optical system when providing the same optical power. Specifically, the metalens 10 can still provide a larger optical power at a lower thickness, so that the volume of the infrared optical system is significantly reduced.

[0100] Φ m / T m -Φ a / T a The lower limit of represents the case where the metalens 10 provides the minimum optical power and the refractive lens 20 provides the maximum optical power in the infrared optical system; Φ m / T m -Φ a / T a The upper limit of represents the case where the metalens 10 provides the maximum optical power and the refractive lens 20 provides the minimum optical power in the optical system.

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

[0102]

[0103] Where p represents a radian of 2π, is the maximum phase value difference provided by the metalens 10, that is, is the difference between the maximum phase and the minimum phase provided by the metalens 10, The unit is rad. m is the effective area radius of the superlens 10, r m The dimension of is a unit of length, such as mm. When the metalens 10 is a double-sided metalens, select For example, when the metalens 10 is a double-sided metalens, both the image side surface of the metalens 10 and the object side surface of the metalens 10 are provided with a micro-nano structure 12. If the maximum phase value provided by the image side surface of the metalens 10 is greater than the maximum phase value provided by the object side surface of the metalens 10, then is the maximum phase value provided by the image side surface of the superlens 10. reflects the spatial phase provided by the superlens 10 in the infrared optical system, The upper limit of represents the maximum spatial phase that the metalens 10 can provide in the infrared optical system, The lower limit represents the minimum spatial phase that the metalens 10 needs to provide when achieving the target optical performance and compressing the volume in the infrared optical system.

[0104] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0105]

[0106] in, is the maximum spatial phase gradient of the superlens 10, is the minimum spatial phase gradient of the metalens 10, and When the metalens 10 is a double-sided metalens, then The surface with the larger difference between the maximum spatial phase gradient and the minimum spatial phase gradient should be used for calculation. For example, if the difference between the maximum spatial phase gradient and the minimum spatial phase gradient on the object side of the metalens 10 is larger than the difference between the maximum spatial phase gradient and the minimum spatial phase gradient on the image side of the metalens 10, then The difference between the maximum spatial phase gradient and the minimum spatial phase gradient on the object side of the metalens 10 is taken. Since the spatial phase gradient determines the deflection ability of the metalens 10 to the light beam, This reflects the range of focusing capabilities that the metalens 10 can provide. The upper limit of represents the maximum focusing range that the metalens 10 can provide in the infrared optical system, The lower limit of represents the minimum focusing range that the metalens 10 can provide in the infrared optical system.

[0107] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0108]

[0109] Among them, f m is the focal length of the superlens 10, D mis the effective area diameter of the superlens 10. In this application, the effective area of ​​the superlens 10 refers to the maximum light transmission area of ​​the superlens 10. F# is the aperture number of the infrared optical system, f m and D m have the same dimension, both are length units, such as mm. (f m / D m )*(1 / F#) reflects the F# improvement effect of the infrared optical system including the refractive lens 20 and the super lens 10 compared with the single-chip super lens 10. (f m / D m )*(1 / F#) represents the maximum F# improvement effect of the infrared optical system provided by the present application, (f m / D m The lower limit of )*(1 / F#) represents the minimum F# improvement effect of the infrared optical system provided by the present application.

[0110] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0111]

[0112] Among them, f is the effective focal length of the infrared optical system, BFL is the optical back focal length of the infrared optical system, in this application, BFL (BackFocalLength, referred to as BFL) is the distance from the image side of the refractive lens 20 to the image plane of the infrared optical system on the optical axis 90, TTL is the total optical length of the infrared optical system, ImgH is the imaging area radius of the infrared optical system on the image plane corresponding to the maximum half field angle, f, BFL, TTL and ImgH have the same dimension, all of which are length units, such as mm. Among them, the ratio of the image height ImgH to the focal length f reflects the field angle of the infrared optical system; the ratio of the optical total length TTL to the optical back focal length BFL reflects the compression of the infrared optical lens corresponding to the infrared optical system. The upper limit of (TTL*ImgH) / (BFL*f) represents the minimum compression capability of the infrared optical lens corresponding to the infrared optical system; the lower limit of (TTL*ImgH) / (BFL*f) represents the strongest compression capability of the infrared optical lens corresponding to the infrared optical system under the premise of ensuring image quality. The value of (TTL*ImgH) / (BFL*f) is between 1.35 and 1.60, which enables the infrared optical system to output better image quality while ensuring a relatively small volume.

[0113] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0114]

[0115] Among them, ΔT is the applicable operating temperature range of the infrared optical system, FOV (Field of view, abbreviated as FOV) is the field of view angle of the infrared optical system, EPD (Entrance Pupil Diameter, abbreviated as EPD) is the entrance pupil diameter of the infrared optical system, the dimension of ΔT is the temperature unit, such as ° C, and the dimension of EPD is the length unit, such as mm. The value of reflects that the infrared optical system has better temperature applicability. Within a specific temperature range, the imaging quality of the infrared optical system is less affected by temperature and still has better imaging quality. The upper limit of represents the case where the infrared optical system has the maximum temperature applicability under a given field of view angle and entrance pupil diameter, and the lower limit of ΔT*ω / EPD represents the case where the infrared optical system has the minimum temperature applicability under a given field of view angle and entrance pupil diameter.

[0116] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0117]

[0118] Among them, Φ m is the focal length provided by the metalens 10 at the central wavelength, Φ m The dimension is D, which is equal to m -1 TTL is the total optical length of the infrared optical system, and the dimension of TTL is a length unit, such as mm. The surface corresponding to the larger maximum curvature of the object side surface of the refractive lens 20 and the image side surface of the refractive lens 20 is the target surface, θ b is the angle between the tangent line at the maximum mechanical diameter of the target surface having curvature and the optical axis 90, for example, see Figure 1 If the maximum curvature radius of the image side surface of the refractive lens 20 is greater than the maximum curvature radius of the object side surface of the refractive lens 20, the image side surface of the refractive lens 20 is the target surface. Figure 1 The maximum mechanical diameter with curvature on the target surface is the edge of the target surface, that is, Figure 1 Point M in the image is drawn, and a tangent line P is drawn through point M. The angle between the tangent line P and the optical axis 90 is θ b It should be noted that the above selection of the target surface is a hypothetical situation, and the selection of the target surface shall be based on the actual situation.

[0119] It should be noted that, for the refractive lens 20, the greater the edge curvature, the greater the processing difficulty. m *cosθ b / TTL reflects the improvement of the processability of the infrared optical system composed of the super lens 10 and the refractive lens 20 for the refractive lens 20. Φ m *cosθ bThe upper limit of / TTL represents the maximum contribution of the superlens 10 to the improvement of the processability of the infrared optical system under a certain total optical length. m *cosθ b The lower limit of / TTL represents the basic contribution of the metalens 10 to the improvement of the processability of the infrared optical system under a certain total optical length.

[0120] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0121]

[0122] Wherein, R1 is the radius of curvature of the object side of the refractive lens 20, R2 is the radius of curvature of the image side of the refractive lens 20, BFL is the optical back focal length of the infrared optical system, L2 is the distance between the object side of the refractive lens 20 and the image side of the metalens 10 on the optical axis 90, and R1, R2, BFL and L2 have the same dimension, which are all length units, such as mm. (R1*BFL) / (R2*L2) reflects the compactness of the infrared optical system. Since the compactness of the infrared optical system is used to measure the distance between each lens, (R1*BFL) / (R2*L2) can also reflect the compression degree of the total optical length of the infrared optical system. The upper limit of (R1*BFL) / (R2*L2) represents the highest compression degree of the infrared optical system, and the total optical length of the infrared optical system is small at this time. The lower limit of (R1*BFL) / (R2*L2) represents the lowest compression degree of the infrared optical system.

[0123] In an optional embodiment, the infrared optical system further satisfies the following conditions:

[0124]

[0125] Among them, T m is the center thickness of the superlens 10, D m is the maximum mechanical diameter of the metalens 10, T a is the center thickness of the refractive lens 20, D a is the maximum mechanical diameter of the refractive lens 20, T m , D m 、T a and D a The dimensions of are the same, both are length units, such as mm. It should be noted that the ratio of the maximum mechanical diameter to the center thickness reflects the space occupation of the lens based on processability and reliability. m / T m -D a / T aThis reflects that the super lens 10 has the advantage of occupying less space than the refractive lens 20 in the infrared optical system. m / T m -D a / T a The upper limit represents the case where the metalens 10 maximizes the advantage of occupying a smaller space than the refractive lens 20. m / T m -D a / T a The lower limit represents the situation where the advantage of the metalens 10 occupying a smaller space than the refractive lens 20 is minimized.

[0126] In an optional embodiment, the infrared optical system further includes an aperture 40, and the aperture 40 is mainly used to control the amount of light entering the infrared optical system.

[0127] In an optional embodiment, the aperture 40 is disposed on the object side of the superlens 10 , that is, there is a preset gap between the aperture 40 and the superlens 10 .

[0128] In an optional embodiment, the aperture 40 is disposed on the image side of the superlens 10 .

[0129] In an optional embodiment, the aperture 40 is disposed on the object side of the superlens 10 .

[0130] In an optional embodiment, the aperture 40 is disposed between the superlens 10 and the refractive lens 20 .

[0131] In an optional embodiment, the aperture stop 40 is disposed on the object side of the refractive lens 20 .

[0132] In an optional embodiment, the infrared optical system further includes a protective glass 50, which is disposed between the refractive lens 20 and the image plane of the infrared optical system. By providing the protective glass 50, the imaging detector to be disposed on the image plane of the infrared optical system can be protected, thereby improving the structural safety of the infrared optical lens.

[0133] In an optional embodiment, the material of the protective glass 50 is silicon.

[0134] To further describe the features of the optical system provided by the embodiments of the present disclosure, the present application exemplarily provides five infrared optical systems that meet the use requirements in five embodiments:

[0135] Example 1

[0136] Figure 1 FIG. 1 shows a schematic diagram of the infrared optical system architecture layout provided in this embodiment. Figure 1In Example 1, the infrared optical system includes a superlens 10, an aperture 40, a refractive lens 20 and a protective glass 50 arranged in sequence from the object side to the image side along the optical axis 90, wherein the aperture 40 is arranged on the image side of the superlens 10, a micro-nano structure 12 is arranged on the image side of the substrate 11 of the superlens 10, and the refractive lens 20 is a spherical lens.

[0137] Table 1-1. Partial system parameters of the infrared optical system provided in Example 1

[0138] parameter data Total optical length (TTL) 3.6mm Maximum field of view (2ω) 73.4° F-number 0.9 Effective focal length 1.26mm Working band 8μm-12μm

[0139] It can be seen from Table 1-1 that the infrared optical system in this embodiment has an F number of 0.9, which can increase the amount of light entering the infrared optical system and collect as much energy entering the infrared optical system as possible when the imaging detector has a low response to light energy, thereby ensuring excellent imaging quality; at the same time, the maximum field of view angle of the infrared optical system is 73.4°, which has a large field of view angle; at the same time, the total optical length is only 3.6 mm, which fully meets the requirements of the infrared optical system for miniaturization and thinness.

[0140] From the object side to the image side, each surface in the infrared optical system is numbered starting from the object side of the superlens 10, and the parameters such as the radius, thickness, and material of each lens surface in the infrared optical system are summarized to obtain Table 1-2.

[0141] Table 1-2. Surface parameters of the infrared optical system provided in Example 1

[0142] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Spherical unlimited 0.30 silicon 2 Metasurface unlimited 0 - 3 Aperture unlimited 0.44 - 4 Spherical -5.4 1.20 silicon 5 Spherical -2.5 1.07 - 6 Spherical unlimited 0.5 silicon 7 Spherical unlimited 0.1 - 8 Image plane unlimited -- --

[0143] Referring to Table 1-2, surface 1 is the object side of the super lens 10, and the radius of curvature of surface 1 is infinite, so surface 1 is a plane, and the distance between it and surface 2 is 0.3 mm, and the material between it and surface 2 is silicon. The micro-nano structure 12 is arranged on the surface of the substrate 11 close to the image side, so surface 2 is recorded as a super surface here, and surface 2 is the image side of the super lens 10, and the radius of curvature of surface 2 is infinite, so surface 2 is a plane, and the distance between it and surface 3 is 0 mm. Surface 3 is the aperture 40, and the radius of curvature of surface 3 is infinite, so surface 3 is a plane, and the distance between it and surface 4 is 0.44 mm, and the material between it and surface 4 is air. Surface 4 is the object side of the refractive lens 20, and its radius of curvature is -5.4 mm, and the distance between it and surface 5 is 1.20 mm, and the material between it and surface 5 is silicon. Surface 5 is the image side surface of the refractive lens 20, and its curvature radius is -2.5 mm. The distance between it and surface 6 is 1.07 mm, and the material between it and surface 6 is air. Surface 6 is the object side surface of the protective glass 50, and the curvature radius of surface 6 is infinite, so surface 6 is a plane, and the distance between it and surface 7 is 0.5 mm, and the material between it and surface 7 is silicon. Surface 7 is the image side surface of the protective glass 50, and the curvature radius of surface 7 is infinite, so surface 7 is a plane, and the distance between it and surface 8 is 0.1 mm, and the material between it and surface 8 is air. Surface 8 is the image surface.

[0144] Figure 2 shows an MTF curve diagram of the infrared optical system provided by the embodiment, Figure 2 The horizontal axis represents the field of view in the Y-axis direction, and its unit is degree. Figure 2 The vertical axis represents the MTF value. Figure 2 The sagittal curve S1 and the meridional curve T1 of MTF with field of view at 21lp / mm spatial frequency, and the sagittal curve S2 and the meridional curve T2 of MTF with field of view at 42lp / mm spatial frequency are listed respectively. It can be seen that at 42lp / mm spatial frequency, the MTF of the infrared optical system within 0.8 field of view (29.36°) is always greater than 0.25, and the image quality of the infrared optical system is better.

[0145] Example 2

[0146] Figure 3 FIG. 2 shows a schematic diagram of the structure layout of the infrared optical system provided in this embodiment. Figure 3 In Example 2, the infrared optical system includes a superlens 10, an aperture 40, a refractive lens 20 and a protective glass 50 arranged in sequence from the object side to the image side along the optical axis 90, wherein a micro-nano structure 12 is arranged on the image side of the substrate 11 of the superlens 10, and the refractive lens 20 is an aspherical lens.

[0147] Table 2-1. Partial parameters of the infrared optical system provided in Example 2

[0148] parameter data Total optical length (TTL) 3.63mm Maximum field of view (2ω) 73.4° F-number 0.9 Effective focal length 1.28mm Working band 8μm-12μm

[0149] According to the direction from the object side to the image side, each surface in the infrared optical system is numbered starting from the object side surface of the superlens 10, and the parameters such as the radius, thickness and material of each lens surface in the infrared optical system are summarized to obtain Table 2-2.

[0150] Table 2-2. Surface parameters of the infrared optical system provided in Example 2

[0151] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Spherical unlimited 0.30 silicon 2 Metasurface unlimited 0 - 3 Aperture unlimited 0.57 - 4 Aspheric -3.5 1.20 silicon 5 Aspheric -2.2 0.99 - 6 Spherical unlimited 0.5 silicon 7 Spherical unlimited 0.1 - 8 Image plane unlimited -- --

[0152] The analysis of Table 2-2 can refer to Example 1 and will not be analyzed again here.

[0153] Surface 4 and surface 5 are even-order aspheric surfaces. After summarizing the surface coefficients of each even-order aspheric surface, we get Table 2-3.

[0154] Table 2-3. Aspheric coefficients in the infrared optical system provided in Example 2

[0155] Surface serial number K 4 times 6 times 8 times 10 times 12 times 14 times 16 times 4 6.7E+00 -9.0E-02 2.3E-02 -6.0E-02 -1.2E-04 -1.5E-03 -4.7E-03 2.0E-02 5 4.5E-01 -5.6E-03 8.3E-05 -5.5E-04 3.6E-05 1.2E-04 -5.8E-06 -1.3E-05

[0156] Figure 4 The MTF curve diagram of the infrared optical system provided by the embodiment is shown, wherein the horizontal axis represents the field of view in the Y-axis direction, and its unit is degree, and the vertical axis represents the MTF value. Figure 4 The sagittal curve S1 and the meridional curve T1 of the MTF with the field of view at 21lp / mm spatial frequency, and the sagittal curve S2 and the meridional curve T2 of the MTF with the field of view at 42lp / mm spatial frequency are listed. It can be seen that at 42lp / mm spatial frequency, the MTF of the infrared optical system within the 0.9 field of view (33°) is always greater than 0.4, and the infrared optical system has excellent image quality.

[0157] Example 3

[0158] Figure 5 FIG. 2 shows a schematic diagram of the structure layout of the infrared optical system provided in this embodiment. Figure 5 In Example 3, the infrared optical system includes a superlens 10, an aperture 40, a refractive lens 20 and a protective glass 50 arranged in sequence from the object side to the image side along the optical axis 90, wherein a micro-nano structure 12 is arranged on the image side surface of the substrate 11 of the superlens 10, and the refractive lens 20 is a spherical lens.

[0159] Table 3-1. Partial parameters of the infrared optical system provided in Example 3

[0160] parameter data Total optical length (TTL) 3.39mm Maximum field of view (2ω) 73.4° F-number 0.9 Effective focal length 1.25mm Working band 8μm-12μm

[0161] According to the direction from the object side to the image side, each surface in the infrared optical system is numbered starting from the object side surface of the superlens 10, and the parameters such as the radius, thickness and material of each lens surface in the infrared optical system are summarized to obtain Table 3-2.

[0162] Table 3-2. Surface parameters of the infrared optical system provided in Example 3

[0163] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Spherical unlimited 0.30 silicon 2 Metasurface unlimited 0 - 3 Aperture unlimited 0.34 - 4 Spherical -5.4 1.20 IRG206 5 Spherical -2.1 0.95 - 6 Spherical unlimited 0.5 silicon 7 Spherical unlimited 0.1 - 8 Image plane unlimited -- --

[0164] The analysis of Table 3-2 can refer to Example 1 and will not be analyzed again here.

[0165] Figure 6 The MTF curve diagram of the infrared optical system provided by the embodiment is shown, wherein the horizontal axis represents the field of view in the Y-axis direction, and its unit is degree, and the vertical axis represents the MTF value. Figure 6 The sagittal curve S1 and the meridional curve T1 of the MTF with the field of view at a spatial frequency of 21lp / mm, and the sagittal curve S2 and the meridional curve T2 of the MTF with the field of view at a spatial frequency of 42lp / mm are listed. It can be seen that at a spatial frequency of 42lp / mm, the MTF of the infrared optical system within a field of view of 0.8 (29.36°) is always greater than 0.2, and the image quality of the infrared optical system is better.

[0166] Example 4

[0167] Figure 7 FIG. 2 shows a schematic diagram of the structure layout of the infrared optical system provided in this embodiment. Figure 7 In Example 4, the infrared optical system includes a superlens 10, an aperture 40, a refractive lens 20 and a protective glass 50 arranged in sequence from the object side to the image side along the optical axis 90, wherein a micro-nano structure 12 is arranged on the image side of the substrate 11 of the superlens 10, and the refractive lens 20 is an aspherical lens.

[0168] Table 4-1. Partial system parameters of the infrared optical system provided in Example 4

[0169] parameter data Total optical length (TTL) 3.41mm Maximum field of view (2ω) 73.4° F-number 0.9 Effective focal length 1.25mm Working band 8μm-12μm

[0170] According to the direction from the object side to the image side, each surface in the infrared optical system is numbered starting from the object side surface of the superlens 10, and the parameters such as the radius, thickness and material of each lens surface in the infrared optical system are summarized to obtain Table 4-2.

[0171] Table 4-2. Surface parameters of the infrared optical system provided in Example 4

[0172]

[0173]

[0174] The analysis of Table 4-2 can refer to Example 1 and will not be analyzed again here.

[0175] Surface 4 and surface 5 are even-order aspheric surfaces. After summarizing the surface coefficients of each even-order aspheric surface, we get Table 4-3.

[0176] Table 4-3. Aspheric coefficients in the infrared optical system provided in Example 4

[0177] Surface serial number K 4 times 6 times 8 times 10 times 12 times 14 times 16 times 3 -1.4E+01 -8.6E-02 -6.3E-02 1.2E-01 -3.6E-04 1.1E-04 1.1E-03 2.7E-03 4 -8.6E-01 3.8E-03 -2.6E-02 1.2E-02 3.0E-05 3.2E-05 2.1E-05 9.7E-06

[0178] Figure 8 The MTF curve diagram of the infrared optical system provided by the embodiment is shown, wherein the horizontal axis represents the field of view in the Y-axis direction, and its unit is degree, and the vertical axis represents the MTF value. Figure 8 The sagittal curve S1 and the meridional curve T1 of the MTF with the field of view at a spatial frequency of 21lp / mm, and the sagittal curve S2 and the meridional curve T2 of the MTF with the field of view at a spatial frequency of 42lp / mm are listed in the figure. It can be seen that at a spatial frequency of 42lp / mm, the MTF of the infrared optical system in the whole field of view is always greater than 0.3, and the imaging quality of the infrared optical system is excellent.

[0179] Example 5

[0180] Fig. 9 FIG. 2 shows a schematic diagram of the structure layout of the infrared optical system provided in this embodiment. Fig. 9 In Example 5, the infrared optical system includes a superlens 10, an aperture 40, a refractive lens 20 and a protective glass 50 arranged in sequence from the object side to the image side along the optical axis 90, wherein a micro-nano structure 12 is arranged on the image side and the object side of the substrate 11 of the superlens 10, and the refractive lens 20 is a spherical lens.

[0181] Table 5-1. Partial optical parameters of the infrared optical system provided in Example 5

[0182]

[0183]

[0184] Each surface in the infrared optical system is numbered from the object side to the image side, and the parameters such as the radius, thickness, and material of each lens surface in the infrared optical system are summarized to obtain Table 5-2.

[0185] Table 5-2. Surface parameters of the infrared optical system provided in Example 5

[0186] Surface serial number Surface type Curvature radius (mm) Thickness(mm) Material 1 Metasurface unlimited 0.30 silicon 2 Metasurface unlimited 0 - 3 Aperture unlimited 0.40 - 4 Spherical -5.6 1.20 silicon 5 Spherical -2.5 1.03 - 6 Spherical unlimited 0.50 silicon 7 Spherical unlimited 0.10 - 8 Image plane unlimited -- --

[0187] The analysis of Table 5-2 can refer to Example 1 and will not be analyzed again here.

[0188] Fig.10 The MTF curve diagram of the infrared optical system provided by the embodiment is shown, wherein the horizontal axis represents the field of view in the Y-axis direction, and its unit is degree, and the vertical axis represents the MTF value. Fig.10 The sagittal curve S1 and the meridional curve T1 of the MTF with the field of view at a spatial frequency of 21lp / mm, and the sagittal curve S2 and the meridional curve T2 of the MTF with the field of view at a spatial frequency of 42lp / mm are listed. It can be seen that at a spatial frequency of 42lp / mm, the MTF of the infrared optical system within a field of view of 0.9 (33°) is always greater than 0.3, and the image quality of the infrared optical system is better.

[0189] After summarizing the various parameters of the infrared optical systems provided by the above five embodiments, the following Table 6 is obtained. Table 6 is mainly used to illustrate that the various conditions satisfied by the infrared optical system 100 provided by the present application are all verified and supported by experiments.

[0190] Table 6. Parameters of the infrared optical system provided in each embodiment

[0191]

[0192]

[0193] The present application also provides an infrared optical lens (not shown), which includes an infrared optical system and an imaging detector as provided in any of the above embodiments. The imaging detector is arranged on the image plane of the infrared optical system to receive light and perform imaging. Referring to the infrared optical system provided in any of the above embodiments, the details of the far-infrared optical system in the far-infrared optical lens will not be repeated here.

[0194] The above is only a specific implementation of the embodiment of the present application, but the protection scope of the embodiment of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed in the embodiment of the present application, which should be included in the protection scope of the embodiment of the present application. Therefore, the protection scope of the embodiment of the present application shall be based on the protection scope of the claims.

Claims

1. An infrared optical system, characterized in that: The invention comprises a super lens (10) and a refractive lens (20) which are sequentially arranged from the object side to the image side along the optical axis (90) of the infrared optical system; wherein the super lens (10) comprises a substrate (11) and a micro-nano structure (12) located on the surface of the substrate (11); the micro-nano structure (12) is arranged on at least one of the image side surface of the substrate (11) and the object side surface of the substrate (11); the object side surface of the refractive lens (20) is convex toward the image side, and the image side surface of the refractive lens (20) is convex toward the image side; The infrared optical system meets the following requirements: Wherein, L1 is the distance between the object side surface of the super lens (10) and the image side surface of the refractive lens (20) on the optical axis (90), and L2 is the thickness of the air gap between the super lens (10) and the refractive lens (20) on the optical axis (90).

2. The infrared optical system according to claim 1, characterized in that: The refractive lens (20) is a spherical lens or an aspherical lens.

3. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Wherein, f is the effective focal length of the infrared optical system, f m is the focal length of the superlens (10).

4. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: 45D≤ΔΦ m ≤100D Among them, ΔΦ m is the difference between the maximum and minimum optical power of the metalens (10) in the working band.

5. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Among them, T m is the center thickness of the metalens (10), T a is the central thickness of the refractive lens (20), Φ m is the focal length provided by the metalens (10) at the central wavelength, Φ a It is the optical focal length provided by the refractive lens (20) at the central wavelength.

6. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Where p represents a radian of 2π, is the maximum phase difference provided by the metalens (10), r m is the effective area radius of the superlens (10).

7. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: in, is the maximum spatial phase gradient of the metalens (10), is the minimum spatial phase gradient of the superlens (10).

8. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Among them, f m is the focal length of the metalens (10), D m is the effective area diameter of the superlens (10), and F# is the aperture number of the infrared optical system.

9. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Among them, f is the effective focal length of the infrared optical system, BFL is the optical back focal length of the infrared optical system, TTL is the total optical length of the infrared optical system, and ImgH is the imaging area radius of the infrared optical system on the image plane corresponding to the maximum half field of view angle.

10. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Wherein, ΔT is the applicable operating temperature range of the infrared optical system, FOV is the field of view of the infrared optical system, and EPD is the entrance pupil diameter of the infrared optical system.

11. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Among them, Φ m is the optical focal length provided by the metalens (10) at the central wavelength, TTL is the total optical length of the infrared optical system; the surface corresponding to the larger maximum curvature of the object side surface of the refractive lens (20) and the image side surface of the refractive lens (20) is the target surface, and the θ b It is the angle between the tangent line at the maximum mechanical diameter of the target surface with curvature and the optical axis (90).

12. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Wherein, R1 is the radius of curvature of the object side surface of the refractive lens (20), R2 is the radius of curvature of the image side surface of the refractive lens (20), BFL is the optical back focal length of the infrared optical system, and L2 is the distance between the object side surface of the refractive lens (20) and the image side surface of the metalens (10) on the optical axis (90).

13. The infrared optical system according to claim 1, characterized in that: The infrared optical system meets the following requirements: Among them, T m is the center thickness of the metalens (10), D m is the maximum mechanical diameter of the metalens (10), T a is the central thickness of the refractive lens (20), D a is the maximum mechanical diameter of the refractive lens (20).

14. The infrared optical system according to claim 1, characterized in that: The infrared optical system further comprises an aperture (40), wherein the aperture (40) is arranged on the object side of the superlens (10); or, the aperture (40) is arranged on the object side of the superlens (10); or, the aperture (40) is arranged on the image side of the superlens (10); or, the aperture (40) is arranged on the object side of the refractive lens (20); or, the aperture (40) is arranged between the superlens (10) and the refractive lens (20).

15. An infrared optical lens, characterized in that: It comprises an imaging detector and an infrared optical system according to any one of claims 1 to 14, wherein the imaging detector is arranged on the image plane of the far-infrared optical system.

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