A face recognition optical system and a face recognition optical lens

Abstract

The present application discloses a face recognition optical system and a face recognition optical lens. The face recognition optical system includes: a first aspheric lens, a second aspheric lens, a super lens, a third aspheric lens, a fourth aspheric lens, a refractive lens, a fifth aspheric lens, and a sixth aspheric lens; the optical power of the first aspheric lens, the fourth aspheric lens, and the sixth aspheric lens are all negative, and the surface of the first aspheric lens close to the object side and the surface close to the image side are both convex to the object side; the optical power of the second aspheric lens, the super lens, the third aspheric lens, the refractive lens, and the fifth aspheric lens are all positive, and the surface of the second aspheric lens close to the object side and the surface close to the image side are both convex to the object side; the surface of the third aspheric lens close to the object side and the surface close to the image side are both convex to the image side; the surface of the refractive lens close to the object side and the surface close to the image side are both convex to the image side. The face recognition optical system has the advantages of excellent imaging quality, small size, and good athermal effect.

Description

Technical Field

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

[0002] Face recognition is a biometric technology that identifies people based on their facial features. A key structure in face recognition devices is the optical system. With the continuous advancement of face recognition technology, in order to accurately identify faces in images through electronic image processing and analysis, the optical system needs to be able to present clearer images.

[0003] In the prior art, although the face recognition optical system can present a relatively clear image, it is large in size and its imaging quality is greatly affected by temperature, which limits the application scenarios of the face recognition optical system. Utility Model Content

[0004] In response to the above technical problems, the embodiments of the present application provide a face recognition optical system and a face recognition optical lens, aiming to provide a face recognition optical system and a face recognition optical lens that have excellent imaging quality, small size, and good thermal aberration effect.

[0005] According to one aspect of an embodiment of the present application, a face recognition optical system is disclosed, which includes, in order from the object side to the image side along the optical axis: a first aspheric lens, a second aspheric lens, a super lens, a third aspheric lens, a fourth aspheric lens, a refractive lens, a fifth aspheric lens, and a sixth aspheric lens; the optical power of the first aspheric lens is negative, and the surface of the first aspheric lens close to the object side is convex toward the object side, and the surface of the first aspheric lens close to the image side is convex toward the object side; the optical power of the second aspheric lens is positive, and the surface of the second aspheric lens close to the object side is convex toward the object side. On the object side, the surface of the second aspheric lens close to the image side is convex toward the object side; the optical focal power of the super lens is positive; the optical focal power of the third aspheric lens is positive, the surface of the third aspheric lens close to the object side is convex toward the image side, and the surface of the third aspheric lens close to the image side is convex toward the image side; the optical focal power of the fourth aspheric lens is negative; the optical focal power of the refractive lens is positive, the surface of the refractive lens close to the object side is convex toward the image side, and the surface of the refractive lens close to the image side is convex toward the image side; the optical focal power of the fifth aspheric lens is positive, and the optical focal power of the sixth aspheric lens is negative.

[0006] In some embodiments, the face recognition optical system satisfies: Among them, f6 is the focal length of the refractive lens, and f is the effective focal length of the face recognition optical system.

[0007] In some embodiments, the face recognition optical system satisfies: Among them, V1 is the Abbe number of the material of the first aspheric lens, V2 is the Abbe number of the material of the second aspheric lens, V4 is the Abbe number of the material of the third aspheric lens, V5 is the Abbe number of the material of the fourth aspheric lens, V6 is the Abbe number of the material of the refractive lens, V7 is the Abbe number of the material of the fifth aspheric lens, and V8 is the Abbe number of the material of the sixth aspheric lens.

[0008] In some embodiments, the face recognition optical system satisfies: Wherein, f1 is the focal length of the first aspheric lens, f6 is the focal length of the refractive lens, f7 is the focal length of the fifth aspheric lens, and f8 is the focal length of the sixth aspheric lens.

[0009] In some embodiments, the face recognition optical system satisfies: Among them, the R 41 is the radius of curvature of the surface of the fourth aspheric lens close to the object side, and the R 42 is the curvature radius of the surface of the fourth aspheric lens close to the image side, and the FNO is the aperture number of the face recognition optical system.

[0010] In some embodiments, the face recognition optical system satisfies: Among them, the ∑CT is the sum of the center thickness of the first aspheric lens, the center thickness of the second aspheric lens, the center thickness of the super lens, the center thickness of the third aspheric lens, the center thickness of the fourth aspheric lens, the center thickness of the refractive lens, the center thickness of the fifth aspheric lens, and the center thickness of the sixth aspheric lens, and the ∑AT is the sum of the thicknesses of the air space between any two adjacent lenses on the optical axis.

[0011] In some embodiments, the face recognition optical system satisfies: Wherein, D1 is the maximum effective diameter of the first aspheric lens, D2 is the maximum effective diameter of the second aspheric lens, D4 is the maximum effective diameter of the third aspheric lens, and D8 is the maximum effective diameter of the sixth aspheric lens.

[0012] In some embodiments, the face recognition optical system satisfies: Among them, the FNO is the aperture number of the face recognition optical system, the f1 is the focal length of the first aspheric lens, the D1 is the maximum effective diameter of the first aspheric lens, the f2 is the focal length of the second aspheric lens, and the D2 is the maximum effective diameter of the second aspheric lens.

[0013] In some embodiments, the refractive lens is an aspherical lens or a spherical lens.

[0014] In some embodiments, the face recognition optical system further includes an aperture;

[0015] The aperture is arranged between any two adjacent lenses;

[0016] or,

[0017] The aperture is arranged on the surface of the first aspheric lens close to the object side;

[0018] or,

[0019] The aperture stop is arranged on the object side of the first aspherical lens.

[0020] In some embodiments, the aperture stop is disposed between the second aspheric lens and the metalens.

[0021] In some embodiments, the face recognition optical system satisfies: Wherein, D8 is the maximum effective diameter of the sixth aspheric lens, EPD is the entrance pupil diameter of the face recognition optical system, and L si It is the distance on the optical axis between the aperture and the image plane of the face recognition optical system working in the visible light band.

[0022] A second aspect of an embodiment of the present application provides a face recognition lens, comprising: an image sensor and a face recognition optical system as described in any one of the above items; the working band of the face recognition optical system includes a visible light band, and the image sensor is arranged on the image plane when the face recognition optical system works in the visible light band.

[0023] In some embodiments, the operating band of the face recognition optical system also includes an infrared band;

[0024] The face recognition lens also includes a filter, which is located between the sixth aspherical lens and the image sensor. The filter includes two non-overlapping areas, and the two areas are used to filter visible light and infrared light respectively; the filter is movably arranged to allow visible light and infrared light to enter the image sensor from the corresponding areas, so that the image plane of the face recognition optical system when working in the infrared band is coplanar with the image plane working in the visible light band.

[0025] The face recognition optical system provided by the present application includes, from the object side to the image side along the optical axis, a first aspheric lens, a second aspheric lens, a super lens, a third aspheric lens, a fourth aspheric lens, a refractive lens, a fifth aspheric lens, and a sixth aspheric lens; the optical power of the first aspheric lens is negative, and the surface of the first aspheric lens close to the object side is convex to the object side, and the surface of the first aspheric lens close to the image side is convex to the object side; the optical power of the second aspheric lens is positive, and the surface of the second aspheric lens close to the object side is convex to the object side. Towards the object side, the surface of the second aspheric lens close to the image side is convex to the object side; the optical power of the super lens is positive; the optical power of the third aspheric lens is positive, the surface of the third aspheric lens close to the object side is convex to the image side, and the surface of the third aspheric lens close to the image side is convex to the image side; the optical power of the fourth aspheric lens is negative; the optical power of the refractive lens is positive, the surface of the refractive lens close to the object side is convex to the image side, and the surface of the refractive lens close to the image side is convex to the image side; the optical power of the fifth aspheric lens is positive, and the optical power of the sixth aspheric lens is negative. In the present application, the face recognition optical system has better imaging quality and smaller size, and the face recognition optical system has good heat elimination effect, so that the face recognition optical system has a wider application scenario. The face recognition optical system can operate in the visible light and near-infrared bands, so that the face recognition optical system can be used both during the day and at night, which can further expand its application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 A schematic diagram of the architectural layout of a face recognition optical system in one embodiment of the present application is shown.

[0028] Figure 2 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at 20°C is shown.

[0029] Figure 3 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at -40°C is shown.

[0030] Figure 4 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at 70°C is shown.

[0031] Figure 5 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at 20°C is shown.

[0032] Figure 6The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at -40°C is shown.

[0033] Figure 7 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at 70°C is shown.

[0034] Figure 8 A schematic diagram of the architectural layout of a face recognition optical system in one embodiment of the present application is shown.

[0035] Fig. 9 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at 20°C is shown.

[0036] Fig.10 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at -40°C is shown.

[0037] Fig.11 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at 70°C is shown.

[0038] Fig.12 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at 20°C is shown.

[0039] Fig.13 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at -40°C is shown.

[0040] Fig.14 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at 70°C is shown.

[0041] Fig.15 A schematic diagram of the architectural layout of a face recognition optical system in one embodiment of the present application is shown.

[0042] Fig.16 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at 20°C is shown.

[0043] Fig.17 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at -40°C is shown.

[0044] Fig.18 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at 70°C is shown.

[0045] Fig.19 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at 20°C is shown.

[0046] Fig. 20 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at -40°C is shown.

[0047] Fig.21 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at 70°C is shown.

[0048] Fig. 22 A schematic diagram of the architectural layout of a face recognition optical system in one embodiment of the present application is shown.

[0049] Fig.23 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at 20°C is shown.

[0050] Fig.24 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at -40°C is shown.

[0051] Fig.25 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the visible light band at 70°C is shown.

[0052] Fig.26 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at 20°C is shown.

[0053] Fig. 27 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at -40°C is shown.

[0054] Fig.28 The MTF field of view curve of the face recognition optical system in one embodiment of the present application working in the near-infrared band at 70°C is shown.

[0055] Reference numerals

[0056] 100. Face recognition optical system;

[0057] 1. The first aspheric lens;

[0058] 2. A second aspheric lens;

[0059] 3. Superlens; 31. Substrate; 32. Micro-nanostructure;

[0060] 4. The third aspheric lens;

[0061] 5. Fourth aspherical lens;

[0062] 6. Refractive lens;

[0063] 7. Fifth aspherical lens;

[0064] 8. Sixth aspherical lens;

[0065] 9. Aperture;

[0066] 10. Protective parts;

[0067] A, object plane; B, image plane; S, optical axis. DETAILED DESCRIPTION

[0068] 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.

[0069] 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.

[0070] See also Figure 1 , Figure 1 FIG. 1 shows a schematic diagram of the structure layout of the face recognition optical system 100 in one 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 optical system is located on the right side of the rightmost lens, that is, the image side is located on the right side of the rightmost lens, and the image plane 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.

[0071] The face recognition optical system 100 includes, in order from the object side to the image side along the optical axis S: a first aspheric lens 1, a second aspheric lens 2, a super lens 3, a third aspheric lens 4, a fourth aspheric lens 5, a refractive lens 6, a fifth aspheric lens 7, and a sixth aspheric lens 8.

[0072] The optical power of the first aspheric lens 1 is negative, the surface of the first aspheric lens 1 close to the object side is convex toward the object side, and the surface of the first aspheric lens 1 close to the image side is convex toward the object side.

[0073] The optical power of the second aspheric lens 2 is positive, the surface of the second aspheric lens 2 close to the object side is convex toward the object side, and the surface of the second aspheric lens 2 close to the image side is convex toward the object side.

[0074] The superlens 3 has positive optical power, and includes a substrate 31 and a micro-nano structure 32 located on the surface of the substrate 31. The micro-nano structure 32 can be arranged on the surface of the substrate 31 facing the object side and / or the image side, and the filling material between the micro-nano structures 32 is air or other materials that are transparent in the working band. 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 32, so that the superlens 3 can achieve the corresponding optical performance.

[0075] The third aspheric lens 4 has positive refractive power, a surface of the third aspheric lens 4 close to the object side is convex toward the image side, and a surface of the third aspheric lens 4 close to the image side is convex toward the image side.

[0076] The refractive power of the fourth aspherical lens 5 is negative.

[0077] The refractive power of the refractive lens 6 is positive, the surface of the refractive lens 6 close to the object side is convex toward the image side, and the surface of the refractive lens 6 close to the image side is convex toward the image side.

[0078] The refractive power of the fifth aspherical lens 7 is positive, and the refractive power of the sixth aspherical lens 8 is negative.

[0079] In the present application, the face recognition optical system 100 has good imaging quality and small size, and the face recognition optical system 100 has good heat elimination effect, so that the face recognition optical system 100 has a wide range of application scenarios, for example, it can be used in electronic devices with a relatively compact structure, and in indoor or outdoor access control. The face recognition optical system 100 can operate in the visible light and near-infrared bands, so that the face recognition optical system 100 can be used both during the day and at night, which can further expand its application scenarios.

[0080] In some embodiments, the micro-nano structure 32 is disposed on a surface of the substrate 31 close to the object side.

[0081] In some embodiments, the surface of the substrate 31 close to the object side and the surface of the substrate 31 close to the image side are both provided with micro-nano structures 32, so that the superlens 3 has a higher degree of design freedom.

[0082] In some embodiments, the micro-nanostructure 32 is a positive micro-nanostructure.

[0083] In some embodiments, the micro-nano structure 32 is a negative micro-nano structure.

[0084] In some embodiments, the micro-nano structure 32 is provided with a layer to make the processing technology of the superlens 3 compatible with the existing semiconductor processing technology, which can facilitate the processing and manufacturing of the superlens 3.

[0085] In some embodiments, the micro-nano structure 32 has two or more layers, so that the superlens 3 has a larger and expected optical focal length.

[0086] For the superlens 3, the position of the micro-nano structure 32, the positive and negative of the micro-nano structure 32, and the number of layers of the micro-nano structure 32 can be freely combined as long as the superlens 3 has the expected optical performance.

[0087] In some embodiments, the specific structure of the metalens 3 is as follows: the surfaces of the substrate 31 close to the object side and the image side are both provided with micro-nano structures 32, and the micro-nano structures 32 on the surface of the substrate 31 close to the object side and the micro-nano structures 32 on the surface of the substrate 31 close to the image side are only provided with one layer, so that the metalens 3 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 3.

[0088] In some embodiments, the working wavelength of the face recognition optical system 100 in the visible light band is 400nm-700nm, and the working wavelength of the face recognition optical system 100 in the infrared band is 825nm-875nm.

[0089] In some embodiments, the image plane of the face recognition optical system 100 working in the visible light band is not coplanar with the image plane working in the infrared band.

[0090] In some embodiments, the face recognition optical system 100 operates in both the visible light band and the infrared band and satisfies the conditional formula 1: Wherein, f6 is the focal length of the refractive lens 6, and f is the effective focal length of the face recognition optical system 100. f6 and f have the same dimension, both of which are length units, such as millimeters.

[0091] Conditional formula 1 reflects the ratio of the focal length of the refractive lens 6 to the effective focal length of the face recognition optical system 100. The relationship between the effective focal lengths of the refractive lens 6 and the face recognition optical system 100 can be reasonably controlled through conditional formula 1, so that the face recognition optical system 100 has a passive temperature compensation function, thereby making the face recognition optical system 100 have good optical performance at -40°C to 70°C.

[0092] In some embodiments, the face recognition optical system 100 operates in both the visible light band and the infrared band and satisfies the conditional formula 2: Among them, V1 is the Abbe number of the material of the first aspheric lens 1, V2 is the Abbe number of the material of the second aspheric lens 2, V4 is the Abbe number of the material of the third aspheric lens 4, V5 is the Abbe number of the material of the fourth aspheric lens 5, V6 is the Abbe number of the material of the refractive lens 6, V7 is the Abbe number of the material of the fifth aspheric lens 7, and V8 is the Abbe number of the material of the sixth aspheric lens 8.

[0093] Conditional formula 2 indicates the dispersion of each lens material except the superlens 3 in the face recognition optical system 100. When the face recognition optical system 100 satisfies conditional formula 2, it reflects that the superlens 3 has a large dispersion adjustment ability in the face recognition optical system 100. At the same time, it can also avoid the problem that the superlens 3 has insufficient light adjustment ability due to the small optical focal length in the face recognition optical system 100. That is, conditional formula 2 can ensure that the superlens 3 has a large dispersion adjustment ability and meets the expected light adjustment ability.

[0094] In some embodiments, the face recognition optical system 100 operates in both the visible light band and the infrared band and satisfies conditional equation 3: Among them, f1 is the focal length of the first aspheric lens 1 , f6 is the focal length of the refractive lens 6 , f7 is the focal length of the fifth aspheric lens 7 , and f8 is the focal length of the sixth aspheric lens 8 .

[0095] Conditional formula 3 reflects the ratio of the product of the focal length of the first aspheric lens 1 and the focal length of the refractive lens 6 to the product of the focal length of the fifth aspheric lens 7 and the focal length of the sixth aspheric lens 8. The upper and lower limits of conditional formula 3 can constrain the focal lengths of the first aspheric lens 1, the refractive lens 6, the fifth aspheric lens 7, and the sixth aspheric lens 8, thereby achieving a reasonable distribution of optical focal lengths, so that the face recognition optical system 100 has better imaging quality at -40°C to 70°C.

[0096] In some embodiments, the face recognition optical system 100 operates in both the visible light band and the infrared band and satisfies conditional formula 4: Among them, R 41 is the radius of curvature of the surface of the fourth aspherical lens 5 close to the object side, R 42is the curvature radius of the surface of the fourth aspherical lens 5 close to the image side, R 41 , R 42 The dimensions of are the same, both are length units, such as millimeters. FNO is the aperture number of the face recognition optical system 100, that is, the F number.

[0097] The upper limit of conditional expression 4 can ensure that the image formed by the incident light of a large field of view in the face recognition optical system 100 has a high relative illumination. The lower limit of conditional expression 4 is used to ensure that the propagation path of the light in the face recognition optical system 100 is smoother, while reducing the tolerance sensitivity of the fourth aspherical lens 5, which can reduce the requirements of the fourth aspherical lens 5 on the processing accuracy to a certain extent.

[0098] In some embodiments, the face recognition optical system 100 satisfies conditional formula 5: Among them, ∑CT is the sum of the center thickness of the first aspheric lens 1, the center thickness of the second aspheric lens 2, the center thickness of the super lens 3, the center thickness of the third aspheric lens 4, the center thickness of the fourth aspheric lens 5, the center thickness of the refractive lens 6, the center thickness of the fifth aspheric lens 7, and the center thickness of the sixth aspheric lens 8. ∑AT is the sum of the thickness of the air space between any two adjacent lenses on the optical axis S. Specifically, ∑AT is the sum of the thickness of the air space between the first aspheric lens 1 and the second aspheric lens 2 on the optical axis S, the thickness of the air space between the second aspheric lens 2 and the super lens 3 on the optical axis S, the thickness of the air space between the super lens 3 and the third aspheric lens 4 on the optical axis S, the thickness of the air space between the third aspheric lens 4 and the fourth aspheric lens 5 on the optical axis S, the thickness of the air space between the fourth aspheric lens 5 and the refractive lens 6 on the optical axis S, the thickness of the air space between the refractive lens 6 and the fifth aspheric lens 7 on the optical axis S, and the thickness of the air space between the fifth aspheric lens 7 and the sixth aspheric lens 8 on the optical axis S. ∑CT and ∑AT have the same dimension, both of which are length units, such as millimeters.

[0099] During the assembly process of the optical system, a spacing element is usually set between two adjacent lenses to maintain a preset distance between the two adjacent lenses. The upper limit of conditional formula five is conducive to controlling the size of the spacing element (not shown) used in the face recognition optical system 100. In the present application, the spacing element can also be used to intercept the stray light path of the edge field of view. The spacing element includes but is not limited to a spacer. The lower limit of conditional formula five can ensure that the face recognition optical system 100 has a relatively compact structure, thereby minimizing the volume of the face recognition optical system 100.

[0100] It should be noted that the size of the lens material and the thickness of the air gap between the lenses are not affected by the working band. Therefore, no matter whether the face recognition optical system 100 works in the visible light band or the near-infrared band, the face recognition optical system 100 satisfies conditional formula five. The same is true for the conditional formulas of the parameters involving size below, so they will not be repeated one by one in the following.

[0101] In some embodiments, the face recognition optical system 100 satisfies conditional formula 6: Wherein, D1 is the maximum effective diameter of the first aspheric lens 1. In the present application, the maximum effective diameter of a lens refers to the diameter of the maximum light transmission area of ​​the lens. D2 is the maximum effective diameter of the second aspheric lens 2, D4 is the maximum effective diameter of the third aspheric lens 4, and D8 is the maximum effective diameter of the sixth aspheric lens 8. D1, D2, D4 and D8 have the same dimension, which is a length unit, such as millimeters.

[0102] The upper limit of conditional formula 6 can ensure that the image formed by the face recognition optical system 100 still has a high relative illumination when facing a larger angle of incidence, so that the brightness of the formed image is relatively uniform. At the same time, the upper limit of conditional formula 6 can also ensure that the face recognition optical system 100 reduces distortion while having good imaging quality. The lower limit of conditional formula 6 is used to control the incident angle of light on each lens, which can avoid the problem of low transmittance due to excessively large incident angles.

[0103] In some embodiments, the face recognition optical system 100 operates in both the visible light band and the infrared band and satisfies conditional equation 7: Wherein, FNO is the aperture number of the face recognition optical system 100, f1 is the focal length of the first aspheric lens 1, D1 is the maximum effective diameter of the first aspheric lens 1, f2 is the focal length of the second aspheric lens 2, and D2 is the maximum effective diameter of the second aspheric lens 2. f1, D1, f2 and D2 have the same dimension, which is a length unit, such as millimeters.

[0104] The upper limit of conditional expression 7 can ensure that the face recognition optical system 100 has a sufficiently large amount of light input, so that the image formed by the face recognition optical system 100 can be clearer and brighter. The lower limit of conditional expression 7 is used to reduce the field curvature of the face recognition optical system 100 and avoid introducing large chromatic aberration, which is conducive to controlling the aberration of the face recognition optical system 100 and can make the face recognition optical system 100 have better imaging quality.

[0105] In some embodiments, the refractive lens 6 is an aspherical lens, which can enable the face recognition optical system 100 to have better performance in aberration control, so that the face recognition optical system 100 has better imaging quality.

[0106] In some embodiments, the refractive lens 6 is a spherical lens. Compared with an aspherical lens, a spherical lens has a lower production cost. Therefore, when the refractive lens 6 is a spherical lens, the production cost of the face recognition optical system 100 can be reduced to a certain extent.

[0107] In some embodiments, the first aspheric lens 1, the second aspheric lens 2, the third aspheric lens 4, the fourth aspheric lens 5, the fifth aspheric lens 7, and the sixth aspheric lens 8 are all made of plastic, and the refractive lens 6 is made of glass. For ease of description, the first aspheric lens 1, the second aspheric lens 2, the third aspheric lens 4, the fourth aspheric lens 5, the fifth aspheric lens 7, and the sixth aspheric lens 8 made of plastic are now recorded as a plastic lens group. Although the refractive index and thermal expansion coefficient of the plastic lens are greatly affected by temperature changes, since the optical focal length of a part of the lenses in the plastic lens group is positive and the optical focal length of the other part is negative, and the optical focal length of each lens in the plastic lens group is reasonably configured, when the temperature changes, the overall focus offset of the plastic lens group is small. At the same time, since the refractive index and thermal expansion coefficient of the glass refractive lens 6 are less affected by temperature, when the temperature changes within a certain range, the imaging quality of the face recognition optical system 100 is less affected by temperature, that is, the face recognition optical system 100 has a good thermal aberration effect.

[0108] Since plastic lenses can be formed by injection molding, they are easy to process. In addition, since the density of plastic is relatively low, up to six plastic lenses are used in the face recognition optical system 100, which includes eight lenses in total, so that the face recognition optical system 100 can be miniaturized and light in weight.

[0109] It should be noted that, for lens materials, plastic material is a general term for a large class of materials, including polycarbonate (PC), polymethyl methacrylate (PMMA), styrene copolymer (AS), polyphenylene ethylene (PS), etc. Therefore, it cannot be understood that the material of each lens in the plastic lens set is the same plastic. It is understandable that a better heat elimination effect can be obtained by reasonably configuring the specific plastic type of each lens in the plastic lens set.

[0110] In a specific embodiment, the materials of the first aspheric lens 1, the second aspheric lens 2, the super lens 3, the third aspheric lens 4, the fourth aspheric lens 5, the fifth aspheric lens 7, and the sixth aspheric lens 8 are all plastic, and the material of the refractive lens 6 is glass. The face recognition optical system 100 has a good thermal aberration effect in the range of -40°C-70°C.

[0111] In some embodiments, the face recognition optical system 100 further includes an aperture 9, which is used to limit the amount of light entering the face recognition optical system 100 to ensure that the face recognition optical system 100 can work effectively and generate high-quality images. The aperture 9 can be set between any two adjacent lenses, or set on the surface of the first aspheric lens 1 close to the object side, or the aperture 9 is set on the object side of the first aspheric lens 1. Specifically, the position where the aperture 9 is set is any of the following:

[0112] (1) The aperture 9 is disposed on the object side of the first aspheric lens 1 , that is, there is a preset distance between the aperture 9 and the first aspheric lens 1 .

[0113] (2) The aperture 9 is arranged on the surface of the first aspheric lens 1 close to the object side;

[0114] (3) The aperture 9 is arranged on the surface of the first aspheric lens 1 close to the image side;

[0115] (4) The aperture 9 is disposed between the first aspheric lens 1 and the second aspheric lens 2, that is, there is a preset distance between the aperture 9 and the first aspheric lens 1, and there is a preset distance between the aperture 9 and the second aspheric lens 2;

[0116] (5) The aperture 9 is arranged on the surface of the second aspheric lens 2 close to the object side;

[0117] (6) The aperture 9 is arranged on the surface of the second aspherical lens 2 close to the image side;

[0118] (7) The aperture 9 is disposed between the second aspheric lens 2 and the super lens 3, that is, there is a preset distance between the aperture 9 and the second aspheric lens 2, and there is a preset distance between the aperture 9 and the super lens 3;

[0119] (8) The aperture 9 is arranged on the surface of the super lens 3 close to the object side;

[0120] (9) The aperture 9 is arranged on the surface of the super lens 3 close to the image side;

[0121] (10) The aperture 9 is disposed between the super lens 3 and the third aspheric lens 4, that is, there is a preset distance between the aperture 9 and the super lens 3, and there is a preset distance between the aperture 9 and the third aspheric lens 4;

[0122] (11) The aperture 9 is arranged on the surface of the third aspheric lens 4 close to the object side;

[0123] (12) The aperture 9 is arranged on the surface of the third aspheric lens 4 close to the image side;

[0124] (13) The aperture 9 is disposed between the third aspheric lens 4 and the fourth aspheric lens 5, that is, there is a preset distance between the aperture 9 and the third aspheric lens 4, and there is a preset distance between the aperture 9 and the fourth aspheric lens 5;

[0125] (14) The aperture 9 is disposed on the surface of the fourth aspherical lens 5 close to the object side;

[0126] (15) The aperture 9 is arranged on the surface of the fourth aspherical lens 5 close to the image side;

[0127] (16) The aperture 9 is disposed between the fourth aspherical lens 5 and the refractive lens 6, that is, there is a preset distance between the aperture 9 and the fourth aspherical lens 5, and there is a preset distance between the aperture 9 and the refractive lens 6;

[0128] (17) The aperture 9 is arranged on the object side of the refractive lens 6;

[0129] (18) The aperture 9 is arranged on the image side of the refractive lens 6;

[0130] (19) The aperture 9 is disposed between the refractive lens 6 and the fifth aspherical lens 7, that is, there is a preset distance between the aperture 9 and the refractive lens 6, and there is a preset distance between the aperture 9 and the fifth aspherical lens 7;

[0131] (20) The aperture 9 is disposed on the surface of the fifth aspheric lens 7 close to the object side;

[0132] (21) The aperture 9 is disposed on the surface of the fifth aspherical lens 7 close to the image side;

[0133] (22) The aperture 9 is disposed between the fifth aspheric lens 7 and the sixth aspheric lens 8;

[0134] (23) The aperture 9 is provided on the surface of the sixth aspherical lens 8 close to the object side.

[0135] In some embodiments, the aperture 9 is disposed between the second aspherical lens 2 and the super lens 3 .

[0136] In some embodiments, under the premise that the aperture 9 is disposed between the second aspherical lens 2 and the super lens 3, the face recognition optical system 100 satisfies conditional formula 7: Wherein, D8 is the maximum effective diameter of the sixth aspherical lens 8, EPD is the entrance pupil diameter of the face recognition optical system 100, and L si is the distance between the aperture 9 and the image plane of the face recognition optical system 100 working in the visible light band. D8, EPD and L si have the same dimension, which is a unit of length, such as millimeter.

[0137] The upper limit of conditional expression 7 is used to constrain the incident ray of the main light on the image sensor adapted to the face recognition optical system 100 at a larger field angle, which can avoid excessive incident angles and thus improve light efficiency. The lower limit of conditional expression 7 is used to control the field curvature and astigmatism of the face recognition optical system 100, so that the face recognition optical system 100 can have better imaging quality at a larger field angle while satisfying a smaller volume.

[0138] In some embodiments, the far-infrared optical system further includes a protective member 10, which can transmit light and is located on a side of the sixth aspheric lens 8 away from the fifth aspheric lens 7 along the optical axis S. The protective member 10 includes but is not limited to protective glass.

[0139] The present application exemplarily provides four face recognition optical systems 100 that meet usage requirements in four embodiments. Next, the face recognition optical systems 100 provided in the various embodiments of the present application are introduced in detail.

[0140] Example 1

[0141] Figure 1 FIG. 1 shows a schematic diagram of the architecture layout of the face recognition optical system 100 provided in Example 1. Figure 1 The face recognition optical system 100 includes, along the optical axis S from the object plane A to the image plane B, a first aspheric lens 1, a second aspheric lens 2, an aperture 9, a super lens 3, a third aspheric lens 4, a fourth aspheric lens 5, a refractive lens 6, a fifth aspheric lens 7, a sixth aspheric lens 8, and a protective member 10, wherein the surface of the substrate 31 close to the object side and the surface of the substrate 31 close to the image side are both provided with a micro-nano structure 32, the refractive lens 6 is a spherical lens, and the protective member 10 is a protective glass. In Example 1, the image plane of the face recognition optical system 100 when working in the visible light of 400nm-700nm and the image plane when working in the near-infrared band of 825nm-875nm are very short, making the two difficult to distinguish, so Figure 1 They are not distinguished in the text and are all recorded as image plane B. Some parameters of the face recognition optical system 100 provided in Example 1 are shown in Table 1-1.

[0142] Table 1-1. Partial parameters of the face recognition optical system 100 provided in Example 1

[0143]

[0144] As can be seen from Table 1-1, the total optical length of the face recognition optical system 100 working in the visible light band of 400nm-700nm is relatively short, only 9.064 mm, which is conducive to the miniaturization of the face recognition optical system 100. The working band of the face recognition optical system 100 is the visible light band of 400nm-700nm and the near infrared band of 825nm-875nm. The effective focal length of the face recognition optical system 100 working in the visible light band of 400nm-700nm is 2.966 mm, and the effective focal length of the face recognition optical system 100 working in the near infrared band of 825nm-875nm is 2.968 mm.

[0145] Starting from the surface of the first aspheric lens 1 close to the object side, along the optical axis S from the object plane A to the image plane B, the surfaces in the face recognition optical system 100 are numbered, and the parameters of each surface are summarized to obtain the following Table 1-2.

[0146] Table 1-2. Parameters of various surfaces in the face recognition optical system 100 provided in Example 1

[0147]

[0148]

[0149] For each surface in Table 1-2, surface 1 is the surface of the first aspheric lens 1 close to the object side, and surface 2 is the surface of the first aspheric lens 1 close to the image side. Surface 3 is the surface of the second aspheric lens 2 close to the object side, and surface 4 is the surface of the second aspheric lens 2 close to the image side. Surface 5 is aperture 9. Surface 6 is the surface of the super lens 3 close to the object side, and surface 7 is the surface of the super lens 3 close to the image side. Surface 8 is the surface of the third aspheric lens 4 close to the object side, and surface 9 is the surface of the third aspheric lens 4 close to the image side. Surface 10 is the surface of the fourth aspheric lens 5 close to the object side, and surface 11 is the surface of the fourth aspheric lens 5 close to the image side. Surface 12 is the surface of the refractive lens 6 close to the object side, and surface 13 is the surface of the refractive lens 6 close to the image side. Surface 14 is the surface of the fifth aspheric lens 7 close to the object side, and surface 15 is the surface of the fifth aspheric lens 7 close to the image side. Surface 16 is the surface of the sixth aspheric lens 8 close to the object side, and surface 17 is the surface of the sixth aspheric lens 8 close to the image side. Surface 18 is the surface of the protective glass close to the object side, and surface 19 is the surface of the protective glass close to the image side. Surface 20 is the image surface of the face recognition optical system 100 working in the 825nm-875nm near-infrared band, and surface 21 is the image surface of the face recognition optical system 100 working in the 400nm-700nm visible light band.

[0150] As can be seen from Table 1-2, surface 1 is an even aspheric surface, the radius of curvature of surface 1 is 54.701 mm, the distance between surface 1 and surface 2 is 0.297 mm, and the refractive index and Abbe number of the material between surface 1 and surface 2 are 1.535 and 56.1 respectively. Surface 2 is an even aspheric surface, the radius of curvature of surface 2 is 3.096 mm, the distance between surface 3 and surface 3 is 0.460 mm, and the material between surface 2 and surface 3 is air. Surface 3 is an even aspheric surface, the radius of curvature of surface 3 is 1.744 mm, the distance between surface 3 and surface 4 is 0.495 mm, and the refractive index and Abbe number of the material between surface 3 and surface 4 are 1.66 and 20.4 respectively. Surface 4 is an even aspheric surface, the radius of curvature of surface 4 is 1.984 mm, the distance between surface 4 and surface 5 is 0.447 mm, and the material between surface 4 and surface 5 is air. Surface 5 is aperture 9, and the radius of curvature of surface 5 is infinite, that is, surface 5 is a plane, and the distance between surface 5 and surface 6 is 0.070 mm. Since the surface of substrate 31 close to the object side and the surface of substrate 31 close to the image side are both provided with micro-nano structures 32, surface 6 and surface 7 are recorded as super surfaces. The radius of curvature of surface 6 is infinite, that is, surface 6 is a plane, and the distance between surface 6 and surface 7 is 0.400 mm. The refractive index and Abbe number of the material between surface 6 and surface 7 are 1.46 and 67.8 respectively. The radius of curvature of surface 7 is infinite, that is, surface 7 is a plane, and the distance between surface 7 and surface 8 is 0.101 mm. The material between surface 7 and surface 8 is air. Surface 8 is an even-order aspheric surface, and the radius of curvature of surface 8 is -20.871 mm. The distance between surface 8 and surface 9 is 0.741 mm. The refractive index and Abbe number of the material between surface 8 and surface 9 are 1.54 and 55.7 respectively. Surface 9 is an even aspheric surface, the radius of curvature of surface 9 is -4.093 mm, the distance between surface 9 and surface 10 is 0.153 mm, and the material between surface 9 and surface 10 is air. Surface 10 is an even aspheric surface, the radius of curvature of surface 10 is 11.987 mm, the distance between surface 10 and surface 11 is 0.352 mm, and the refractive index and Abbe number of the material between surface 10 and surface 11 are 1.66 and 20.4 respectively. Surface 11 is an even aspheric surface, the radius of curvature of surface 11 is 4.390 mm, the distance between surface 11 and surface 12 is 0.109 mm, and the material between surface 11 and surface 12 is air. Surface 12 is a spherical surface, the radius of curvature of surface 12 is -493.523 mm, the distance between surface 12 and surface 13 is 1.667 mm, and the refractive index and Abbe number of the material between surface 12 and surface 13 are 1.77 and 49.6 respectively. Surface 13 is a spherical surface, the radius of curvature of surface 13 is -3.168 mm, the distance between surface 13 and surface 14 is 0.079 mm, and the material between surface 13 and surface 14 is air.Surface 14 is an even aspheric surface, the radius of curvature of surface 14 is -4.344 mm, the distance between surface 14 and surface 15 is 0.561 mm, and the refractive index and Abbe number of the material between surface 14 and surface 15 are 1.54 and 56.0 respectively. Surface 15 is an even aspheric surface, the radius of curvature of surface 15 is -1.438 mm, the distance between surface 15 and surface 16 is 0.050 mm, and the material between surface 15 and surface 16 is air. Surface 16 is an even aspheric surface, the radius of curvature of surface 16 is 1.246 mm, the distance between surface 16 and surface 17 is 0.333 mm, and the refractive index and Abbe number of the material between surface 16 and surface 17 are 1.66 and 20.4 respectively. Surface 17 is an even-order aspheric surface, the radius of curvature of surface 17 is 0.781 mm, the distance between surface 17 and surface 18 is 2.349 mm, and the material between surface 17 and surface 18 is air. Surface 18 is a spherical surface, the radius of curvature of surface 18 is infinite, that is, surface 18 is a plane, and the distance between surface 18 and surface 19 is 0.300 mm. Surface 19 is a spherical surface, the radius of curvature of surface 19 is infinite, that is, surface 19 is a plane, and the distance between surface 19 and surface 21 is 0.100 mm. The distance between surface 20 and surface 21 is -0.004 mm, and the negative sign in "-0.004" indicates that surface 20 is on the object side of surface 21.

[0151] Surface 1, surface 2, surface 3, surface 4, surface 8, surface 9, surface 10, surface 11, surface 14, surface 15, surface 16, and surface 17 are all even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0152]

[0153] Among them, Z(r) is the distance vector height from the vertex of the aspherical surface when the aspherical surface is at a height of r along the optical axis S direction; c is the surface curvature of the aspherical surface, c=1 / R, R is the 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 1, Surface 2, Surface 3, Surface 4, Surface 8, Surface 9, Surface 10, Surface 11, Surface 14, Surface 15, Surface 16, Surface 17 can all be obtained from Table 1-3.

[0154] Table 1-3. Coefficients of various orders of even-order aspheric surfaces in the face recognition optical system 100 provided in Example 1

[0155]

[0156] Please refer to Table 1-3. Taking surface 1 as an example, the k of surface 1 is 9.900E+01, A is 6.650E-02, B is -1.400E-02, C is 3.844E-03, D is -2.212E-04, E is 1.082E-04, and F is -6.701E-05. The k, A, B, C, D, E, and F values ​​of surface 2, surface 3, surface 4, surface 8, surface 9, surface 10, surface 11, surface 14, surface 15, surface 16, and surface 17 can be queried from Table 1-3 with reference to surface 1, and will not be elaborated here one by one.

[0157] See also Figure 2 , Figure 2 The MTF (Modulation Transfer Function, MTF for short) field of view curve of the face recognition optical system 100 provided in Example 1 working in the visible light band of 400nm-700nm at 20°C is shown. Figure 2 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Figure 2 The vertical axis in the figure is the MTF value. MTF is an important indicator used to describe the imaging quality of an optical system. The larger the MTF value, the better the imaging quality. Figure 2 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Figure 2 It can be seen that, at a spatial frequency of 250 lp / mm, the MTF value of the face recognition optical system 100 within a 0.9 field of view (2.97 mm image height) is greater than 0.25, and the imaging quality of the face recognition optical system 100 is relatively good.

[0158] See also Figure 3 , Figure 3 The MTF field of view curve of the face recognition optical system 100 provided in Example 1 working at -40°C in the visible light band of 400nm-700nm is shown. Figure 3 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Figure 3 The vertical axis is the MTF value. Figure 3 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Figure 3It can be seen that, at a spatial frequency of 250 lp / mm, the MTF value of the face recognition optical system 100 within a 0.8 field of view (2.64 mm image height) is greater than 0.2, and the imaging quality of the face recognition optical system 100 is relatively good.

[0159] See also Figure 4 , Figure 4 The MTF field of view curve of the face recognition optical system 100 provided in Example 1 working in the visible light band of 400nm-700nm at 70°C is shown. Figure 4 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Figure 4 The vertical axis is the MTF value. Figure 4 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Figure 4 It can be seen that, at a spatial frequency of 250 lp / mm, the MTF value of the face recognition optical system 100 within a 0.8 field of view (2.64 mm image height) is greater than 0.2, and the imaging quality of the face recognition optical system 100 is relatively good.

[0160] Depend on Figures 2 to 4 It can be seen that within the range of -40°C-70°C, the imaging quality of the face recognition optical system 100 provided in Example 1 in the 400nm-700nm visible light band is less affected by temperature. Therefore, the face recognition optical system 100 provided in Example 1 has a good thermal aberration effect in the visible light band.

[0161] See also Figure 5 , Figure 5 The MTF field of view curve of the face recognition optical system 100 provided in Example 1 working in the near-infrared band of 825nm-875nm at 20°C is shown. Figure 5 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Figure 5 The vertical axis is the MTF value. Figure 5 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Figure 5It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.35, and the imaging quality of the face recognition optical system 100 is better.

[0162] See also Figure 6 , Figure 6 The MTF field of view curve of the face recognition optical system 100 provided in Example 1 working at -40°C in the near-infrared band of 825nm-875nm is shown. Figure 6 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Figure 6 The vertical axis is the MTF value. Figure 6 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Figure 6 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.35, and the imaging quality of the face recognition optical system 100 is better.

[0163] See also Figure 7 , Figure 7 The MTF field of view curve of the face recognition optical system 100 provided in Example 1 working at 70° C. in the near-infrared band of 825 nm-875 nm is shown. Figure 7 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Figure 7 The vertical axis is the MTF value. Figure 7 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Figure 7It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.2; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the 0.9 field of view (2.97 mm image height) is greater than 0.35, and the imaging quality of the face recognition optical system 100 is better.

[0164] Depend on Figures 5 to 7 It can be seen that within the range of -40°C-70°C, the imaging quality of the face recognition optical system 100 provided in Example 1 in the near-infrared band of 825nm-875nm is less affected by temperature. Therefore, the face recognition optical system 100 provided in Example 1 has a good thermal aberration effect in the near-infrared band.

[0165] Example 2

[0166] Figure 8 FIG. 1 shows a schematic diagram of the architecture layout of the face recognition optical system 100 provided in Example 2. Figure 8 The face recognition optical system 100 includes, along the optical axis S from the object plane A to the image plane B, a first aspheric lens 1, a second aspheric lens 2, an aperture 9, a super lens 3, a third aspheric lens 4, a fourth aspheric lens 5, a refractive lens 6, a fifth aspheric lens 7, a sixth aspheric lens 8, and a protective member 10, wherein the surface of the substrate 31 close to the object side and the surface of the substrate 31 close to the image side are both provided with a micro-nano structure 32, the refractive lens 6 is an aspheric lens, and the protective member 10 is a protective glass. Regarding the image plane B of the face recognition optical system 100 in Example 2, the image plane when the face recognition optical system 100 works in the visible light of 400nm-700nm is B2, and the image plane when the face recognition optical system 100 works in the near-infrared band of 825nm-875nm is B1. Some parameters of the face recognition optical system 100 provided in Example 2 are shown in Table 2-1.

[0167] Table 2-1. Partial parameters of the face recognition optical system 100 provided in Example 2

[0168]

[0169] As can be seen from Table 2-1, the total optical length of the face recognition optical system 100 working in the visible light band of 400nm-700nm is relatively short, only 9.065 mm, which is conducive to the miniaturization of the face recognition optical system 100. The working band of the face recognition optical system 100 is the visible light band of 400nm-700nm and the near infrared band of 825nm-875nm. The effective focal length of the face recognition optical system 100 working in the visible light band of 400nm-700nm is 2.975 mm, and the effective focal length of the face recognition optical system 100 working in the near infrared band of 825nm-875nm is 2.979 mm.

[0170] Starting from the surface of the first aspheric lens 1 close to the object side, along the optical axis S from the object plane A to the image plane B, the surfaces in the face recognition optical system 100 are numbered, and the parameters of each surface are summarized to obtain the following Table 2-2.

[0171] Table 2-2. Parameters of various surfaces in the face recognition optical system 100 provided in Example 2

[0172]

[0173]

[0174] The analysis of each surface in Table 2-2 can refer to Example 1, and the analysis will not be repeated in this example.

[0175] Surfaces 1 to 4 and surfaces 8 to 17 are all even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0176]

[0177] 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 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 surfaces 1 to 4 and surfaces 8 to 17 can be obtained from Table 2-3.

[0178] Table 2-3. Coefficients of the even-order aspheric surfaces in the face recognition optical system 100 provided in Example 2

[0179]

[0180]

[0181] For the method of obtaining the coefficients of each order of the even-order aspheric surface of each surface in Table 2-3, reference can be made to Example 1, which will not be repeated in this example.

[0182] See also Fig. 9 , Fig. 9 The MTF field of view curve of the face recognition optical system 100 provided in Example 2 working in the visible light band of 400nm-700nm at 20°C is shown. Fig. 9 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig. 9 The vertical axis is the MTF value. Fig. 9 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig. 9 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 in the full field of view (3.3 mm image height) is greater than 0.2; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 in the full field of view (3.3 mm image height) is greater than 0.5, and the imaging quality of the face recognition optical system 100 is better.

[0183] See also Fig.10 , Fig.10 The MTF field of view curve of the face recognition optical system 100 provided in Example 2 working at -40°C in the visible light band of 400nm-700nm is shown. Fig.10 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.10 The vertical axis is the MTF value. Fig.10 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.10 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.9 field of view (2.97 mm image height) is greater than 0.2; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.38, and the imaging quality of the face recognition optical system 100 is better.

[0184] See also Fig.11 , Fig.11 The MTF field of view curve of the face recognition optical system 100 provided in Example 2 working in the visible light band of 400nm-700nm at 70°C is shown. Fig.11 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.11 The vertical axis is the MTF value. Fig.11 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.11 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.8 field of view (2.64 mm image height) is greater than 0.2, and when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.48, and the imaging quality of the face recognition optical system 100 is better.

[0185] Depend on Figures 9 to 11 It can be seen that within the range of -40°C-70°C, the imaging quality of the face recognition optical system 100 provided in Example 2 in the 400nm-700nm visible light band is less affected by temperature. Therefore, the face recognition optical system 100 provided in Example 2 has a good thermal aberration effect in the visible light band.

[0186] See also Fig.12 , Fig.12 The MTF field of view curve of the face recognition optical system 100 provided in Example 2 working in the near-infrared band of 825nm-875nm at 20°C is shown. Fig.12 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.12 The vertical axis is the MTF value. Fig.12 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.12 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.28; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.4, and the imaging quality of the face recognition optical system 100 is better.

[0187] See also Fig.13 , Fig.13The MTF field of view curve of the face recognition optical system 100 provided in Example 1 working at -40°C in the near-infrared band of 825nm-875nm is shown. Fig.13 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.13 The vertical axis is the MTF value. Fig.13 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.13 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.28; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.45, and the imaging quality of the face recognition optical system 100 is better.

[0188] See also Fig.14 , Fig.14 The MTF field of view curve of the face recognition optical system 100 provided in Example 1 working at 70° C. in the near-infrared band of 825 nm-875 nm is shown. Fig.14 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.14 The vertical axis is the MTF value. Fig.14 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.14 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the 0.9 field of view (2.97 mm image height) is greater than 0.38, and the imaging quality of the face recognition optical system 100 is better.

[0189] Depend on Figure 12 to Figure 14It can be seen that within the range of -40°C-70°C, the imaging quality of the face recognition optical system 100 provided in Example 2 in the near-infrared band of 825nm-875nm is less affected by temperature. Therefore, the face recognition optical system 100 provided in Example 2 has a good thermal aberration effect in the near-infrared band.

[0190] Example 3

[0191] Fig.15 FIG. 1 shows a schematic diagram of the architecture layout of the face recognition optical system 100 provided in Example 3. Fig.15 The face recognition optical system 100 includes, along the optical axis S from the object plane A to the image plane B, a first aspheric lens 1, a second aspheric lens 2, an aperture 9, a super lens 3, a third aspheric lens 4, a fourth aspheric lens 5, a refractive lens 6, a fifth aspheric lens 7, a sixth aspheric lens 8, and a protective member 10, wherein the surface of the substrate 31 close to the object side and the surface of the substrate 31 close to the image side are both provided with a micro-nano structure 32, the refractive lens 6 is an aspheric lens, and the protective member 10 is a protective glass. In Example 3, the image plane of the face recognition optical system 100 when working in the visible light of 400nm-700nm and the image plane when working in the near-infrared band of 825nm-875nm are very short, making it difficult to distinguish between the two, so Fig.15 They are not distinguished in the text and are uniformly recorded as image plane B. Some parameters of the face recognition optical system 100 provided in Example 3 are shown in Table 3-1.

[0192] Table 3-1. Partial parameters of the face recognition optical system 100 provided in Example 3

[0193]

[0194] As can be seen from Table 3-1, the total optical length of the face recognition optical system 100 working in the visible light band of 400nm-700nm is relatively short, only 8.927 mm, which is conducive to the miniaturization of the face recognition optical system 100. The working band of the face recognition optical system 100 is the visible light band of 400nm-700nm and the near infrared band of 825nm-875nm. The effective focal length of the face recognition optical system 100 working in the visible light band of 400nm-700nm is 2.902 mm, and the effective focal length of the face recognition optical system 100 working in the near infrared band of 825nm-875nm is 2.905 mm.

[0195] Starting from the surface of the first aspheric lens 1 close to the object side, along the optical axis S from the object plane A to the image plane B, the surfaces in the face recognition optical system 100 are numbered, and the parameters of each surface are summarized to obtain the following Table 3-2.

[0196] Table 3-2. Parameters of various surfaces in the face recognition optical system 100 provided in Example 3 The analysis of each surface in Table 3-2 can refer to Example 1, and the analysis will not be repeated in this example.

[0197] Surfaces 1 to 4 and surfaces 8 to 17 are all even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0198]

[0199] 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 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 surfaces 1 to 4 and surfaces 8 to 17 can be obtained from Table 3-3.

[0200] Table 3-3. Coefficients of the even-order aspheric surfaces in the face recognition optical system 100 provided in Example 3

[0201]

[0202] For the method of obtaining the coefficients of each order of the even-order aspheric surface of each surface in Table 3-3, reference can be made to Example 1, which will not be repeated in this example.

[0203] See also Fig.16 , Fig.16 The MTF field of view curve of the face recognition optical system 100 provided in Example 3 working in the visible light band of 400nm-700nm at 20°C is shown. Fig.16 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.16 The vertical axis is the MTF value. Fig.16 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.16 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 in the full field of view (3.3 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 in the full field of view (3.3 mm image height) is greater than 0.5, and the imaging quality of the face recognition optical system 100 is better.

[0204] See also Fig.17 , Fig.17 The MTF field of view curve of the face recognition optical system 100 provided in Example 3 working in the visible light band of 400nm-700nm at -40°C is shown. Fig.17 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.17 The vertical axis is the MTF value. Fig.17 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.17 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the full field of view of 0.9 (2.97 mm image height) is greater than 0.2; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view of 0.9 (2.97 mm image height) is greater than 0.5, and the imaging quality of the face recognition optical system 100 is better.

[0205] See also Fig.18 , Fig.18 The MTF field of view curve of the face recognition optical system 100 provided in Example 3 working in the visible light band of 400nm-700nm at 70°C is shown. Fig.18 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.18 The vertical axis is the MTF value. Fig.18 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.18 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.8 field of view (2.64 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.42, and the imaging quality of the face recognition optical system 100 is better.

[0206] Depend on Figures 16 to 18It can be seen that within the range of -40°C-70°C, the imaging quality of the face recognition optical system 100 provided in Example 3 in the 400nm-700nm visible light band is less affected by temperature. Therefore, the face recognition optical system 100 provided in Example 3 has a good thermal aberration effect in the visible light band.

[0207] See also Fig.19 , Fig.19 The MTF field of view curve of the face recognition optical system 100 provided in Example 3 working in the near-infrared band of 825nm-875nm at 20°C is shown. Fig.19 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.19 The vertical axis is the MTF value. Fig.19 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.19 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.4, and the imaging quality of the face recognition optical system 100 is better.

[0208] See also Fig. 20 , Fig. 20 The MTF field of view curve of the face recognition optical system 100 provided in Example 3 working at -40°C in the near-infrared band of 825nm-875nm is shown. Fig. 20 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig. 20 The vertical axis is the MTF value. Fig. 20 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig. 20It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 in the full field of view (3.3 mm image height) is greater than 0.2; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 in the full field of view (3.3 mm image height) is greater than 0.5, and the imaging quality of the face recognition optical system 100 is better.

[0209] See also Fig.21 , Fig.21 The MTF field of view curve of the face recognition optical system 100 provided in Example 3 working in the near-infrared band of 825nm-875nm at 70° C. is shown. Fig.21 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.21 The vertical axis is the MTF value. Fig.21 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.21 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the 0.9 field of view (2.97 mm image height) is greater than 0.4, and the imaging quality of the face recognition optical system 100 is better.

[0210] Depend on Figures 19 to 21 It can be seen that within the range of -40°C-70°C, the imaging quality of the face recognition optical system 100 provided in Example 3 in the near-infrared band of 825nm-875nm is less affected by temperature. Therefore, the face recognition optical system 100 provided in Example 3 has a good thermal aberration effect in the near-infrared band.

[0211] Example 4

[0212] Fig. 22 FIG. 1 shows a schematic diagram of the architecture layout of the face recognition optical system 100 provided in Example 4. Fig. 22The face recognition optical system 100 includes, along the optical axis S from the object plane A to the image plane B, a first aspheric lens 1, a second aspheric lens 2, an aperture 9, a super lens 3, a third aspheric lens 4, a fourth aspheric lens 5, a refractive lens 6, a fifth aspheric lens 7, a sixth aspheric lens 8, and a protective member 10, wherein the micro-nano structure 32 is disposed on the surface of the substrate 31 close to the image side, the refractive lens 6 is an aspheric lens, and the protective member 10 is a protective glass. In Example 4, the image plane of the face recognition optical system 100 when working in the visible light of 400nm-700nm is very short from the image plane when working in the near-infrared band of 825nm-875nm, making it difficult to distinguish between the two, so Fig. 22 They are not distinguished in the text and are uniformly recorded as image plane B. Some parameters of the face recognition optical system 100 provided in Example 4 are shown in Table 4-1.

[0213] Table 4-1. Partial parameters of the face recognition optical system 100 provided in Example 4

[0214]

[0215] As can be seen from Table 4-1, the total optical length of the face recognition optical system 100 working in the visible light band of 400nm-700nm is relatively short, only 8.114 mm, which is conducive to the miniaturization of the face recognition optical system 100. The working band of the face recognition optical system 100 is the visible light band of 400nm-700nm and the near infrared band of 825nm-875nm. The effective focal length of the face recognition optical system 100 working in the visible light band of 400nm-700nm is 2.925 mm, and the effective focal length of the face recognition optical system 100 working in the near infrared band of 825nm-875nm is 2.928 mm.

[0216] Starting from the surface of the first aspheric lens 1 close to the object side, along the optical axis S from the object plane A to the image plane B, the surfaces in the face recognition optical system 100 are numbered, and the parameters of each surface are summarized to obtain the following Table 4-2.

[0217] Table 4-2. Parameters of various surfaces in the face recognition optical system 100 provided in Example 4

[0218]

[0219]

[0220] The analysis of each surface in Table 4-2 can refer to Example 1, and the analysis will not be repeated in this example.

[0221] Surfaces 1 to 4, 8 to 11, and 14 to 17 are all even-order aspheric surfaces, and their surface shapes satisfy the following relationship:

[0222]

[0223] 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 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 surfaces 1 to 4, surfaces 8 to 11, and surfaces 14 to 17 can all be obtained from Table 4-3.

[0224] Table 4-3. Coefficients of the even-order aspheric surfaces in the face recognition optical system 100 provided in Example 4

[0225]

[0226] For the method of obtaining the coefficients of each order of the even-order aspheric surfaces of each surface in Table 4-3, reference can be made to Example 1, which will not be repeated in this example.

[0227] See also Fig.23 , Fig.23 The MTF field of view curve of the face recognition optical system 100 provided in Example 4 working in the visible light band of 400nm-700nm at 20°C is shown. Fig.23 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.23 The vertical axis is the MTF value. Fig.23 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.23 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 in the full field of view (3.3 mm image height) is greater than 0.2; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 in the full field of view (3.3 mm image height) is greater than 0.5, and the imaging quality of the face recognition optical system 100 is better.

[0228] See also Fig.24 , Fig.24 The MTF field of view curve of the face recognition optical system 100 provided in Example 4 working at -40°C in the visible light band of 400nm-700nm is shown. Fig.24The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.24 The vertical axis is the MTF value. Fig.24 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.24 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.8 field of view (2.64 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.4, and the imaging quality of the face recognition optical system 100 is better.

[0229] See also Fig.25 , Fig.25 The MTF field of view curve of the face recognition optical system 100 provided in Example 4 working in the visible light band of 400nm-700nm at 70°C is shown. Fig.25 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.25 The vertical axis is the MTF value. Fig.25 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.25 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.9 field of view (2.97 mm image height) is greater than 0.2; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.48, and the imaging quality of the face recognition optical system 100 is better.

[0230] Depend on Figure 23 to Figure 25 It can be seen that within the range of -40°C-70°C, the imaging quality of the face recognition optical system 100 provided in Example 4 in the 400nm-700nm visible light band is less affected by temperature. Therefore, the face recognition optical system 100 provided in Example 4 has a good thermal aberration effect in the visible light band.

[0231] See also Fig.26 , Fig.26The MTF field of view curve of the face recognition optical system 100 provided in Example 4 working in the near-infrared band of 825nm-875nm at 20°C is shown. Fig.26 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.26 The vertical axis is the MTF value. Fig.26 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.26 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.42, and the imaging quality of the face recognition optical system 100 is better.

[0232] See also Fig. 27 , Fig. 27 The MTF field of view curve of the face recognition optical system 100 provided in Example 4 working at -40°C in the near-infrared band of 825nm-875nm is shown. Fig. 27 The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig. 27 The vertical axis is the MTF value. Fig. 27 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig. 27 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.2; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the full field of view (3.3 mm image height) is greater than 0.40, and the imaging quality of the face recognition optical system 100 is better.

[0233] See also Fig.28 , Fig.28 The MTF field of view curve of the face recognition optical system 100 provided in Example 1 working at 70° C. in the near-infrared band of 825 nm-875 nm is shown. Fig.28The horizontal axis in is the image height, that is, the horizontal axis measures the field of view with the image height, and its unit is millimeters. Fig.28 The vertical axis is the MTF value. Fig.28 The sagittal curve S1 and the meridional curve T1 of the MTF with a spatial frequency of 62.5lp / mm as the field of view changes, the sagittal curve S2 and the meridional curve T2 of the MTF with a spatial frequency of 125lp / mm as the field of view changes, and the sagittal curve S3 and the meridional curve T3 of the MTF with a spatial frequency of 250lp / mm as the field of view changes. Fig.28 It can be seen that when the spatial frequency is 250lp / mm, the MTF value of the face recognition optical system 100 within the 0.6 field of view (1.98 mm image height) is greater than 0.25; when the spatial frequency is 125lp / mm, the MTF value of the face recognition optical system 100 within the 0.9 field of view (2.97 mm image height) is greater than 0.28, and the imaging quality of the face recognition optical system 100 is better.

[0234] Depend on Figure 26 to Figure 28 It can be seen that within the range of -40°C-70°C, the imaging quality of the face recognition optical system 100 provided in Example 4 in the near-infrared band of 825nm-875nm is less affected by temperature. Therefore, the face recognition optical system 100 provided in Example 4 has a good thermal aberration effect in the near-infrared band.

[0235] After summarizing the various parameters of the face recognition optical system 100 provided in the above four embodiments, the following Tables 5 and 6 are obtained. The display of Tables 5 and 6 is mainly used to illustrate that the various conditions satisfied by the face recognition optical system 100 provided in this application are all verified and supported by experiments.

[0236] Table 5. Parameters of the face recognition optical system 100 provided in various embodiments working in the visible light band

[0237]

[0238]

[0239] Table 6. Various parameters of the face recognition optical system 100 provided in various embodiments working in the near infrared band

[0240]

[0241]

[0242] The present application also provides a face recognition optical lens (not shown), which includes an image sensor and any of the above-mentioned face recognition optical systems 100. The working band of the face recognition optical system 100 includes the visible light band, and the image sensor is arranged on the image plane when the face recognition optical system 100 works in the visible light band. The image sensor includes but is not limited to CMOS (Complementary Metal Oxide Semiconductor, CMOS for short) and CCD (Charge Coupled Device, CCD for short).

[0243] In some embodiments, the working band of the face recognition optical system 100 also includes an infrared band. Specifically, the working band of the face recognition optical system 100 also includes a near-infrared band of 825nm-875nm.

[0244] The face recognition lens also includes a filter, which is located between the sixth aspherical lens 8 and the image sensor. The filter includes two non-overlapping areas, the two areas have a preset thickness, and the two areas are used to filter visible light and near-infrared light, respectively. The filter is movably arranged, and the position of the filter is changed by driving the filter so that visible light and near-infrared light enter the image sensor from the corresponding areas, and the optical path of the near-infrared light incident into the face recognition lens is changed by the filter, so that the image plane of the face recognition optical system 100 when working in the near-infrared band is coplanar with the image plane working in the visible light band.

[0245] In some embodiments, the filter can be rotatably arranged, and the filter includes a first area and a second area that do not overlap each other. The first area is used to filter near-infrared light, and visible light can pass through the first area to enter the image sensor. The second area is used to filter visible light, and near-infrared light can pass through the second area to enter the image sensor. When the face recognition lens works in the visible light band, by rotating the filter, the light incident into the face recognition lens passes through the first area of ​​the filter to enter the image sensor. When the face recognition lens works in the near-infrared band, by rotating the filter, the light incident into the face recognition lens passes through the second area of ​​the filter to enter the image sensor. By configuring the thickness of the first area and the second area, the optical path of the near-infrared light incident into the face recognition lens is changed, so that the image plane of the face recognition optical system 100 when working in the near-infrared band can be coplanar with the image plane working in the visible light band.

[0246] In some embodiments, the filter can be set in translation, and the filter includes a first area and a second area that do not overlap each other. The first area is used to filter near-infrared light, and visible light can pass through the first area to enter the image sensor. The second area is used to filter visible light, and near-infrared light can pass through the second area to enter the image sensor. When the face recognition lens works in the visible light band, the filter is controlled to move horizontally, and the light incident into the face recognition lens passes through the first area of ​​the filter to enter the image sensor. When the face recognition lens works in the near-infrared band, the filter is controlled to move horizontally, and the light incident into the face recognition lens passes through the second area of ​​the filter to enter the image sensor. By configuring the thickness of the first area and the second area, the optical path of the near-infrared light incident into the face recognition lens is changed, so that the image plane of the face recognition optical system 100 when working in the near-infrared band can be coplanar with the image plane working in the visible light band.

[0247] In the present application, since the image plane of the face recognition optical system 100 when working in the near-infrared band is coplanar with the image plane working in the visible light band, and the image plane of the face recognition optical system 100 when working in the visible light band, the face recognition lens can clearly image in both the visible light band and the near-infrared band. Therefore, the face recognition lens can be used not only in an environment with sufficient sunlight, but also in a dark environment with supplementary near-infrared light.

[0248] 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 face recognition optical system, characterized in that: The face recognition optical system includes, from the object side to the image side along the optical axis, a first aspheric lens, a second aspheric lens, a super lens, a third aspheric lens, a fourth aspheric lens, a refractive lens, a fifth aspheric lens, and a sixth aspheric lens; the optical power of the first aspheric lens is negative, the surface of the first aspheric lens close to the object side is convex toward the object side, and the surface of the first aspheric lens close to the image side is convex toward the object side; the optical power of the second aspheric lens is positive, the surface of the second aspheric lens close to the object side is convex toward the object side, and the second aspheric lens The surface close to the image side is convex to the object side; the optical focal length of the super lens is positive; the optical focal length of the third aspheric lens is positive, the surface of the third aspheric lens close to the object side is convex to the image side, and the surface of the third aspheric lens close to the image side is convex to the image side; the optical focal length of the fourth aspheric lens is negative; the optical focal length of the refractive lens is positive, the surface of the refractive lens close to the object side is convex to the image side, and the surface of the refractive lens close to the image side is convex to the image side; the optical focal length of the fifth aspheric lens is positive, and the optical focal length of the sixth aspheric lens is negative.

2. The face recognition optical system according to claim 1, characterized in that: The face recognition optical system meets the following requirements: Among them, f6 is the focal length of the refractive lens, and f is the effective focal length of the face recognition optical system.

3. The face recognition optical system according to claim 1, characterized in that: The face recognition optical system meets the following requirements: Among them, V1 is the Abbe number of the material of the first aspheric lens, V2 is the Abbe number of the material of the second aspheric lens, V4 is the Abbe number of the material of the third aspheric lens, V5 is the Abbe number of the material of the fourth aspheric lens, V6 is the Abbe number of the material of the refractive lens, V7 is the Abbe number of the material of the fifth aspheric lens, and V8 is the Abbe number of the material of the sixth aspheric lens.

4. The face recognition optical system according to claim 1, characterized in that: The face recognition optical system meets the following requirements: Wherein, f1 is the focal length of the first aspheric lens, f6 is the focal length of the refractive lens, f7 is the focal length of the fifth aspheric lens, and f8 is the focal length of the sixth aspheric lens.

5. The face recognition optical system according to claim 1, characterized in that: The face recognition optical system meets the following requirements: Among them, the R 41 is the radius of curvature of the surface of the fourth aspheric lens close to the object side, and the R 42 is the curvature radius of the surface of the fourth aspheric lens close to the image side, and the FNO is the aperture number of the face recognition optical system.

6. The face recognition optical system according to claim 1, characterized in that: The face recognition optical system meets the following requirements: Among them, the ∑CT is the sum of the center thickness of the first aspheric lens, the center thickness of the second aspheric lens, the center thickness of the super lens, the center thickness of the third aspheric lens, the center thickness of the fourth aspheric lens, the center thickness of the refractive lens, the center thickness of the fifth aspheric lens, and the center thickness of the sixth aspheric lens, and the ∑AT is the sum of the thicknesses of the air space between any two adjacent lenses on the optical axis.

7. The face recognition optical system according to claim 1, characterized in that: The face recognition optical system meets the following requirements: Wherein, D1 is the maximum effective diameter of the first aspheric lens, D2 is the maximum effective diameter of the second aspheric lens, D4 is the maximum effective diameter of the third aspheric lens, and D8 is the maximum effective diameter of the sixth aspheric lens.

8. The face recognition optical system according to claim 1, characterized in that: The face recognition optical system meets the following requirements: Among them, the FNO is the aperture number of the face recognition optical system, the f1 is the focal length of the first aspheric lens, the D1 is the maximum effective diameter of the first aspheric lens, the f2 is the focal length of the second aspheric lens, and the D2 is the maximum effective diameter of the second aspheric lens.

9. The face recognition optical system according to any one of claims 1 to 8, characterized in that: The refractive lens is an aspherical lens or a spherical lens.

10. The face recognition optical system according to any one of claims 1 to 8, characterized in that: The face recognition optical system also includes an aperture; The aperture is arranged between any two adjacent lenses; or, The aperture is arranged on the surface of the first aspheric lens close to the object side; or, The aperture stop is arranged on the object side of the first aspherical lens.

11. The face recognition optical system according to claim 10, characterized in that: The aperture is arranged between the second aspheric lens and the super lens.

12. The face recognition optical system according to claim 11, characterized in that: The face recognition optical system meets the following requirements: Wherein, D8 is the maximum effective diameter of the sixth aspheric lens, EPD is the entrance pupil diameter of the face recognition optical system, and L si It is the distance on the optical axis between the aperture and the image plane of the face recognition optical system working in the visible light band.

13. A face recognition optical lens, characterized in that: include: An image sensor and a face recognition optical system as described in any one of claims 1 to 12; the working band of the face recognition optical system includes the visible light band, and the image sensor is arranged on the image plane when the face recognition optical system works in the visible light band.

14. The face recognition optical lens according to claim 13, characterized in that: The working band of the face recognition optical system also includes an infrared band; The face recognition lens also includes a filter, which is located between the sixth aspherical lens and the image sensor. The filter includes two non-overlapping areas, and the two areas are used to filter visible light and infrared light respectively; the filter is movably arranged to allow visible light and infrared light to enter the image sensor from the corresponding areas, so that the image plane of the face recognition optical system when working in the infrared band is coplanar with the image plane working in the visible light band.

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