Iris lens and iris recognition device

Abstract

The utility model relates to the field of biological recognition, in particular to an iris lens and an iris recognition device. The iris lens sequentially comprises a first lens, a second lens, a third lens and a fourth lens from an object space to an image space along an optical axis, the first lens is a convex-concave double-face aspheric lens and comprises a first aspheric surface and a second aspheric surface, and the first lens is made of PC; an aperture stop; the second lens is a convex-concave double-sided aspheric lens and comprises a third aspheric surface and a fourth aspheric surface, and the third aspheric surface and the fourth aspheric surface are made of E48R; the parallel flat plate optical filter comprises a first flat plate surface and a second flat plate surface which are made of K9 glass; the total length of the iris lens is 3.376281 mm, the focal length of the iris lens is 2.041765 mm, and the F number of the iris lens is 2.099. The iris imaging device is small in size, convenient to carry, clear in imaging, uniform and bright in image, small in iris image deformation and excellent in imaging performance.

Description

Technical Field

[0001] This utility model relates to the field of biometrics, and in particular to an iris lens and an iris recognition device. Background Technology

[0002] Biometric technology aims to identify individuals through their inherent physiological or behavioral characteristics, such as fingerprint recognition, facial recognition, and iris recognition. Among these, iris recognition, due to its high accuracy, stability, and uniqueness, has shown great application potential in numerous fields such as security, finance, and healthcare. The iris, a ring-shaped tissue located between the pupil and sclera in the eye, has a unique texture structure determined by random factors in the embryonic development environment; even identical twins will have different iris textures. The iris lens, as a key component of the iris recognition system, directly affects the accuracy and stability of the entire system. Early iris recognition devices were bulky and expensive, limiting their large-scale application. With continuous advancements in optical, electronic, and image processing technologies, iris lenses have gradually evolved towards miniaturization, higher resolution, and lower power consumption.

[0003] Despite significant advancements in iris recognition technology, several challenges remain. In pursuing high resolution, it's crucial to minimize the F-number (the ratio of the system's focal length to the entrance pupil diameter). However, a smaller ratio leads to more severe aberrations (especially chromatic aberration). Severe aberrations not only directly impact image quality but can also cause excessive heat to enter the system. Excessive heat can affect the temperature of optical components, negatively impacting imaging performance. Furthermore, iris recognition devices have specific requirements for the optical distance and viewing angle needed to acquire clear iris images. These requirements often result in larger device sizes, compromising portability. Utility Model Content

[0004] Therefore, the technical problem to be solved by this utility model is to overcome the problem that the iris lens in the prior art faces serious aberrations at high resolution, which affects image quality and heat, as well as the defects of large device size and poor portability due to specific optical distance and viewing angle requirements.

[0005] To solve the above-mentioned technical problems, this utility model provides an iris lens, which includes, along the optical axis from the object side to the image side, the following components in sequence:

[0006] The first lens is a double-sided aspherical lens with both convex and concave surfaces, and its material is PC, comprising:

[0007] The first aspherical surface has a radius of curvature of 0.831 mm and a conic coefficient of -4.557. The coefficients of the aspherical surface equation are a2 = 0, a4 = -0.445, a6 = -2.11, a8 = -9.275, and a... 10 =-18.804, a12 = 13.946;

[0008] a second aspherical surface having a radius of curvature of 0.37 mm, a conic constant of -1.035, aspherical equation coefficients a2=0, a4=-4.082, a6=9.51, a8=-20.14, a 10 = 24.854, a 12 = -12.267, and a vertex distance of 0.39 mm from the vertex of the first aspherical surface;

[0009] a stop having a distance of 0.277 mm from the vertex of the second aspherical surface;

[0010] a second lens which is a convex-concave double aspherical lens made of E48R and comprising:

[0011] a third aspherical surface having a radius of curvature of 0.573 mm, a conic constant of -2.354, aspherical equation coefficients a2=0, a4=0.322, a6=-1.169, a8=2.155, a 10 = -5.25, a 12 = 1.575, and a vertex distance of 0.1 mm from the stop;

[0012] a fourth aspherical surface having a radius of curvature of -3.697 mm, a conic constant of -128.561, aspherical equation coefficients a2=0, a4=6.440x10 -4 , a6=0.96, a8=-5.197, a 10 = 5.166, a 12 = 0.352, and a vertex distance of 0.8 mm from the vertex of the third aspherical surface;

[0013] a parallel plate filter made of K9 glass and comprising:

[0014] a first plate surface having a distance of 0.8 mm from the vertex of the fourth aspherical surface;

[0015] a second plate surface having a distance of 0.2 mm from the first plate surface;

[0016] an image sensing element comprising:

[0017] a sensing surface having a distance of 0.81 mm from the second plate surface.

[0018] Preferably, the first aspheric surface has a clear aperture of 0.6mm, the second aspheric surface has a clear aperture of 0.6mm, the diaphragm surface in the diaphragm has a clear aperture of 0.55mm, the third aspheric surface has a clear aperture of 0.56mm, the fourth aspheric surface has a clear aperture of 0.56mm, the first flat surface has a clear aperture of 0.6mm, the second flat surface has a clear aperture of 0.6mm, and the photosensitive surface has a clear aperture of 0.262mm.

[0019] Preferably, the total length of the iris lens is 3.376281mm, the focal length of the iris lens is 2.041765mm, and the F number is 2.099.

[0020] Preferably, the working wavelength of the iris lens is 785nm to 900nm, and the main wavelength is 850nm.

[0021] Preferably, the refractive index of the first lens for the main wavelength of 850nm is 1.585, the refractive index of the second lens for the main wavelength of 850nm is 1.531, and the refractive index of the parallel flat filter for the main wavelength of 850nm is 1.51.

[0022] Preferably, the field of view angle of the iris lens is 0°, 2.5°, 5°, 7.5°.

[0023] Preferably, when the field of view angle of the iris lens is 7.5°, the root mean square diameter is 0.956μm, when the field of view angle is 5°, the root mean square diameter is 0.724μm, when the field of view angle is 2.5°, the root mean square diameter is 0.500μm, and when the field of view angle is 0°, the root mean square diameter is 0.405μm.

[0024] Preferably, the image sensing element is any one of a CCD image sensor and a CMOS imaging sensor.

[0025] Preferably, when the image sensing element is a CMOS imaging sensor, the pixel unit size of the CMOS imaging sensor is 1.12μm.

[0026] The utility model also provides an iris recognition device, including above -mentioned iris lens.

[0027] The above technical scheme of the utility model has the following advantages compared with the prior art:

[0028] The utility model relates to an iris lens, through the field of view angle of iris lens is 0 DEG, 2.5 DEG, 5 DEG, 7.5 DEG, ensure that the iris image contains enough features to identify, can capture the whole iris, since in the practical application scene of iris recognition, the lens needs to frequently carry out iris image acquisition, the material of first lens is PC material, can make it can withstand frequent light impact and mechanical vibration, increase the durability of iris lens, and PC material can be in the initial stage of light incidence to the light of different wavelengths better preliminary separation, the second lens material is E48R, can utilize its own characteristics to these light more fine processing, make the imaging performance of whole iris lens under different wavelengths more balanced, improve the image quality. With the iris lens focal length 2mm as the target, determine the initial curvature radius of each aspheric surface and the initial distance between each part of the iris lens, not only ensure that the iris lens can realize high-resolution imaging, accurately capture iris details, but also can effectively control the lens volume, convenient to carry, satisfy the demand of the equipment portability in practical application, in addition, in order to further optimize the imaging effect of lens, by observing MTF curve and Spt diagram, the influence of different aberrations is balanced, such as spherical aberration, coma, field curvature and the like, the curvature radius of each aspheric surface, conic coefficient and aspheric surface equation coefficient and the distance between each part of the iris lens are corrected, and the optimal parameter combination value is found through iterative optimization, so that the iris lens can short-distance imaging clearly, reach the best imaging quality, and the image clarity and accuracy are improved significantly. In conclusion, the iris lens designed in the utility model makes the iris lens have high resolution while effectively reducing aberration, ensuring the imaging quality, and has the advantages of small size and convenient carrying, and can better meet the actual application demand in the field of iris recognition. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to make the content of the utility model more easily understood clearly, the utility model is further explained in detail below according to the specific embodiment of the utility model and combining with the drawings, wherein:

[0030] Figure 1 It is a structure schematic diagram of the utility model kind iris lens.

[0031] Figure 2 It is the modulation transfer function curve of different fields of view of the utility model kind iris lens under 1 / 2 Nyquist frequency.

[0032] Figure 3 It is the point list diagram of the utility model kind iris lens.

[0033] Figure 4 It is the field curvature and optical distortion structure schematic diagram of the utility model kind iris lens.

[0034] Figure 5 is a relative luminance curve of the iris lens. DETAILED DESCRIPTION

[0035] The utility model will be further described below in combination with the drawings and specific embodiments, so that the person skilled in the art can better understand the utility model and can be implemented, but the embodiment is not as the limitation of the utility model.

[0036] Referring to Figure 1 The utility model embodiment one provides an iris lens, and the object side to the image side includes successively along the optical axis:

[0037] The first lens 1 is convex-concave double-sided aspheric lens, and the material is PC, and it includes:

[0038] The first aspheric surface 11 has a curvature radius of 0.831mm, a conic coefficient of -4.557, an aspheric equation coefficient a2=0, a4=-0.445, a6=-2.11, a8=-9.275, a 10 =-18.804, a 12 =13.946;

[0039] The second aspheric surface 12 has a curvature radius of 0.37mm, a conic coefficient of -1.035, an aspheric equation coefficient a2=0, a4=-4.082, a6=9.51, a8=-20.14, a 10 =24.854, a 12 =-12.267, and the distance d1 between the vertex and the vertex of the first aspheric surface 11 is 0.39mm;

[0040] The aperture diaphragm 2 has a distance d2 of 0.277mm with the vertex of the second aspheric surface 12;

[0041] The second lens 3 is convex-concave double-sided aspheric lens, and the material is E48R, and it includes:

[0042] The third aspheric surface 31 has a curvature radius of 0.573mm, a conic coefficient of -2.354, an aspheric equation coefficient a2=0, a4=0.322, a6=-1.169, a8=2.155, a 10 =-5.25, a 12 =1.575, and the distance d3 between the vertex and the aperture diaphragm 2 is 0.1mm;

[0043] The fourth aspheric surface 32 has a curvature radius of -3.697mm, a conic coefficient of -128.561, an aspheric equation coefficient a2=0, a4=6.440×10 -4 , a6=0.96, a8=-5.197, a10 = 5.166, a 12 = 0.352, the vertex distance d4 = 0.8 mm from the vertex of the third aspherical surface 31;

[0044] The parallel flat filter 4 is made of K9 glass and comprises:

[0045] The first flat surface 41 is at a distance d5 = 0.8 mm from the vertex of the fourth aspherical surface;

[0046] The second flat surface 42 is at a distance d6 = 0.2 mm from the first flat surface 41;

[0047] The image sensing element 5 comprises:

[0048] The image sensing surface is at a distance d7 = 0.81 mm from the second flat surface 42.

[0049] The first lens 1 has a first aspherical surface 11 on the object side, a second aspherical surface 12 on the image side, the second lens 3 has a third aspherical surface 31 on the object side and a fourth aspherical surface 32 on the image side, the parallel flat filter 4 has a first flat surface 41 on the object side and a second flat surface 42 on the image side.

[0050] The utility model discloses a high resolution can guarantee image quality size, namely in the case where F number is small enough, reduce such as spherical aberration, coma, field curvature and so on aberration, and F number is the ratio of system focal length and entrance pupil diameter, and the focal length determination needs to consider many factors, the size of imaging sensor, working distance etc., if the focal length is too short, can lead to image too enlarged, and peripheral information is sacrificed, if the focal length is too long, can lead to image definition deficiency, therefore the utility model will target focal length be 2mm.

[0051] In the embodiment, preferably, the field of view angle of the iris lens is 0°, 2.5°, 5° or 7.5°.

[0052] In order to ensure that the iris image contains enough features for identification, a sufficient field of view angle is needed to capture the entire iris, therefore the field of view angle is set to 0°, 2.5°, 5° or 7.5°, and based on the focal length and the field of view angle, the entrance pupil diameter is set. The small F number of the iris lens ensures high resolution imaging and accurate capture of iris details, and effectively controls the size of the lens, facilitating portability and meeting the demand for device portability in practical applications.

[0053] The refractive indexes of lenses of different materials are different, which affects the focal length of the lens, and in the actual application scene of iris recognition, the lens needs to frequently collect iris images, the material of the first lens 1 is PC material, which can withstand frequent light impact and mechanical vibration, increase the durability of the iris lens, and the PC material can better separate different wavelengths of light in the initial stage of light incidence, the material of the second lens 3 is E48R, which can use its own characteristics to process these lights more finely, so that the imaging performance of the whole iris lens under different wavelengths is more balanced, and the image quality is improved.

[0054] In the embodiment, specifically, the refractive index of the first lens 1 for the main wavelength of 850nm is 1.585, the refractive index of the second lens 3 for the main wavelength of 850nm is 1.531, and the refractive index of the parallel plate filter 4 for the main wavelength of 850nm is 1.51.

[0055] After determining the material of the iris lens, taking the focal length of 2mm as the target, the initial curvature radius of each aspheric surface and the initial distance between each part of the iris lens are determined through the MTF (modulation transfer function) curve.

[0056] In the design of the iris lens, under the condition that other conditions remain unchanged, when the initial curvature radius of the first aspheric surface 11 or the second aspheric surface 12 is increased, the focal length of the iris lens will be increased accordingly, and vice versa, reducing the initial curvature radius of the first aspheric surface 11 or the second aspheric surface 12 will reduce the focal length of the iris lens. Similarly, increasing the initial curvature radius of the third aspheric surface 31 and the fourth aspheric surface 32 will also result in an increase in the focal length, and reducing the initial curvature radius will shorten the focal length.

[0057] When the focal length of the whole optical system is less than the target focal length of 2mm, the distance between each part of the iris lens needs to be considered, for example, the distance between the vertex of the second aspheric surface 12 and the aperture stop 2, or the distance between the vertex of the third aspheric surface 31 and the vertex of the fourth aspheric surface 32 can be increased to increase the focal length of the system, and when the focal length of the system is greater than the target focal length, the distance between the aperture stop 2 and the vertex of the third aspheric surface 31 can be used to shorten the focal length, so that the focal length of the system is closer to the target value.

[0058] Although the initial curvature radius of each aspheric surface and the initial distance between each part of the iris lens can meet certain basic optical requirements and provide a basic framework for imaging, due to the complexity of the optical system, there will inevitably be aberrations and other problems, which will negatively affect the imaging quality and cause the image to appear blurred, distorted, etc. Therefore, it is necessary to further optimize the parameters of the iris lens.

[0059] Specifically, the design of the first and second lenses involves multiple coefficients and has a relatively complex structure. Each aspherical coefficient corresponds to a different radius of curvature and direction. They are interconnected and influence each other. Changes in the aspherical coefficients will directly affect the focal length, distortion, and other image quality indicators of the first and second lenses.

[0060] Based on the above, parameter optimization was carried out with a focal length of 2mm. By observing the MTF (modulation transfer function) curve and the point plot (Spt) diagram, the lens's ability to transmit image details at different spatial frequencies was analyzed in depth. This yielded optimized parameters such as the radius of curvature of each aspherical surface, the conic coefficient, the coefficients of the aspherical equation, and the distances between different parts of the iris lens. The MTF curve can intuitively reflect the imaging performance of the lens and provide an important basis for parameter optimization.

[0061] like Figure 2 As shown, Figure 2 This diagram shows the modulation transfer function (MTF) curves of an iris lens at 1 / 2 Nyquist frequency for different fields of view. When observing the MTF curves, the horizontal axis represents spatial frequency, measured in line pairs per millimeter (line cycles per millimeter). This reflects the richness of detail in the image; a higher spatial frequency indicates finer resolvable details. The vertical axis represents the OFT modulus, used to measure the optical system's ability to transfer different spatial frequencies. The closer the OFT modulus is to 1, the stronger the system's ability to reproduce details at that spatial frequency.

[0062] Figure 2 The image presents multiple curves, showcasing the modulation transfer function curves under different fields of view. The modulation function for different fields of view is represented by two directions: tangential (T) and radial (S). These two directions can more comprehensively reflect the characteristics of the optical system in transmitting image details at different angles.

[0063] In iris recognition lenses, there are specific requirements for the modulation transfer function (MTU): at the half Nyquist frequency, the MTU for a 0.707 field of view must be greater than 0.4. The Nyquist frequency is a crucial parameter related to image sensors, determining the highest spatial frequency the sensor can resolve. In this embodiment, the Nyquist frequency of the chip used is 446 lp / mm, and the half Nyquist frequency is 223 lp / mm. At this frequency, the MTU of this invention is greater than 0.4 for the 0.707 field of view, ensuring high image quality and clear reproduction of image details.

[0064] During the optimization process, different adjustment strategies are adopted to address aberration issues. If spherical aberration is too large, it can be reduced by increasing the radius of curvature of each aspherical surface, thereby improving image quality, reducing light scattering and deviation, and ultimately improving image sharpness. Conversely, if spherical aberration is insufficient (i.e., the lens is too flat), the radius of curvature of each aspherical surface needs to be reduced to increase the system's focusing ability, allowing light to be focused more accurately on the imaging plane.

[0065] Observe the distribution characteristics of points in the Spt plot. If the points in the Spt plot are no longer concentrated at a single point, but instead exhibit a comet-like distribution, then the iris lens has coma. If the points at the edge of the field of view show obvious deformation, dispersion, or asymmetrical distribution, and the distribution of points at the edge of the field of view is no longer circular or nearly circular, but rather elliptical or irregular in shape, and the distribution range of the points may be much larger than that of the central field of view, then it indicates that the iris lens has aberration problems at the edge of the field of view. When coma or edge aberration is found, it is necessary to adjust the distance between the various parts of the iris lens to improve these aberrations. However, increasing the distance between the various parts of the iris lens may reduce coma, but it will also increase other aberrations, such as spherical aberration. Therefore, it is necessary to comprehensively weigh the impact of different aberrations, and iteratively optimize the lens by using an evaluation function that includes penalties for various aberrations such as spherical aberration, coma, and field curvature, continuously trying different parameter combinations, observing the changes in aberrations, and finally finding the optimal parameter combination to achieve the best imaging performance of the lens.

[0066] like Figure 3 As shown, Figure 3 This utility model discloses a dot plot of an iris lens. The dot plot reflects the geometric structure of the entire system's imaging. For an iris lens, the root mean square diameter of the light spot within a 0.5 field of view must be within the pixel unit range, because the 0.5 field of view covers the region of the iris with the richest texture and most prominent features, which is the core part for extracting key identification information. For example, the subtle stripes, crypts, and other unique features of the iris are mostly concentrated in this area, and these features constitute each person's unique biometric identifier. Accurately capturing the image of this region is key to achieving high-precision iris recognition, directly affecting the accuracy and reliability of the recognition. Therefore, it is the most critical and valuable area in the iris recognition image.

[0067] In this embodiment, specifically, when the field of view of the iris lens is 7.5° (0.707 field of view), the root mean square diameter is 0.956 μm; when the field of view is 5° (0.5 field of view), the root mean square diameter is 0.724 μm; when the field of view is 2.5° (0.3 field of view), the root mean square diameter is 0.500 μm; and when the field of view is 0° (0 field of view), the root mean square diameter is 0.405 μm.

[0068] Therefore, the iris lens can effectively reduce and balance the coma, marginal aberration and other aberrations, and can maintain good imaging performance under different fields of view.

[0069] In the process of designing and optimizing the iris lens, the clear aperture is also an important parameter that cannot be ignored, the imaging quality of the iris lens is comprehensively affected by various factors, and the size of the clear aperture directly affects the amount of light incident into the optical system, the larger the aperture, the more light can be collected, and the higher the brightness of the system.

[0070] However, although the larger clear aperture has advantages in light collection and imaging quality improvement, the larger the clear aperture of the iris lens, the higher the cost and the larger the volume, which undoubtedly brings inconvenience to the portability of the equipment, in the design of the present iris lens, the value of the clear aperture is automatically output after optimizing the curvature radius of each aspherical surface, the distance between each part of the iris lens, etc.

[0071] After outputting the clear aperture of each part of the iris lens, in order to ensure that the iris lens has good imaging performance while considering the requirements of cost control and portability, by observing the MTF (modulation transfer function) curve, the value of the clear aperture is further appropriately increased to find a best balance point between imaging quality, cost and portability, so that the lens can better meet the requirements of practical application.

[0072] In the embodiment, preferably, the clear aperture of the first aspherical surface 11 is 0.6mm, the clear aperture of the second aspherical surface 12 is 0.6mm, the clear aperture of the aperture stop surface of the aperture stop 2 is 0.55mm, the clear aperture of the third aspherical surface 31 is 0.56mm, the clear aperture of the fourth aspherical surface 32 is 0.56mm, the clear aperture of the first flat surface 41 is 0.6mm, the clear aperture of the second flat surface 42 is 0.6mm, and the clear aperture of the photosensitive surface 51 is 0.262mm.

[0073] In the embodiment, specifically, the image photosensitive element 5 is any one of a CCD image sensor and a CMOS imaging sensor.

[0074] In this embodiment, preferably, when the image sensing element 5 is a CMOS imaging sensor, the pixel unit size of the CMOS imaging sensor is 1.12 μm. In the 0.5 field of view range, which is the area richest in iris texture and most characteristic, the pixel unit size can ensure that fine features (such as fine stripes, crypts, etc.) are clearly recorded, thereby providing a clear and accurate image basis for subsequent high-precision iris recognition, and the root mean square diameter of 0.707 field of view is 1.57 μm, indicating that the imaging quality of the entire image plane is very good. The pixel unit size of 1.12 μm ensures high resolution while realizing a relatively compact CMOS imaging sensor design, making the entire iris lens small and compact.

[0075] As shown in Table 1, Table 1 is a specific parameter table of the iris lens.

[0076] Table 1

[0077]

[0078]

[0079] As shown in Table 2, Table 2 is a specific parameter table of each aspheric surface.

[0080] Table 2

[0081]

[0082] In summary, the total length of the iris lens according to the present application is 3.376281 mm, the focal length f of the iris lens is 2.041765 mm, the F number F# is 2.099, the working waveband range is 785 nm to 900 nm, and the main wavelength λ is 850 nm. ′

[0083] Compared with existing iris lenses, the present application greatly reduces the total length of the iris lens while ensuring image quality, which makes it exhibit unique advantages in many practical application scenarios. First, it can be used for mobile phone security protection, and the lens with a total length of only 3.38 mm can be installed on a mobile phone for mobile phone unlocking, better protecting user privacy and property safety. In small-sized devices such as smart door locks and mobile payment terminals, the compact size facilitates integration and does not require excessive internal space, allowing the device to be designed to be lighter, thinner, and more compact, thereby improving the overall portability and aesthetics of the product. Second, for security monitoring systems, the iris lens with reduced size can be flexibly installed in various hidden corners to expand the monitoring range and reduce installation costs without the need for complex fixing brackets. Third, the shorter lens length can effectively reduce material costs, and this cost advantage will be more pronounced in mass production, making the iris recognition technology more competitive in the market.

[0084] As Figure 4 ​As shown, Figure 4 This is a schematic diagram of the field curvature and optical distortion structure of an iris lens according to this invention. Observe the field curvature and distortion, specifically the meridional field curvature (denoted by T) and the sagittal field curvature (denoted by S). For imaging systems, the smaller the field curvature, the clearer the image. Distortion affects image distortion but does not affect image sharpness. For general imaging systems, distortion is required to be within 3%, as image distortion is imperceptible to the naked eye within this range. In iris recognition systems, to improve the accuracy of feature matching, distortion should be minimized. The field curvature of the lens in this invention is 0.011 mm, the optical distortion within a 0.5 field of view is less than 0.6%, and the optical distortion within a 0.707 field of view at the dominant wavelength (850 nm) is less than 1.288%. Therefore, the iris lens of this invention exhibits excellent performance in field curvature and distortion control. The extremely small field curvature ensures image sharpness, and the optical distortion, far below conventional standards, lays a solid foundation for high-precision feature matching in iris recognition, greatly improving the reliability and stability of iris recognition.

[0085] like Figure 5 As shown, Figure 5 This invention discloses a relative illumination curve for an iris lens. When observing a relative illumination curve, relative illumination refers to the ratio of the illumination at the edge of the field of view to that at the center. The higher this ratio, the brighter the edge of the field of view. For imaging systems, a relative illumination greater than 50% is generally required. Above this value, the human eye can hardly perceive the difference in illumination between the center and edge of the field of view. For iris recognition lenses, due to their high requirements for image quality, the relative illumination requirements are even more stringent. In the iris lens proposed in this invention, the relative illumination is greater than 99% in all fields of view. This excellent performance means that the lens can achieve extremely uniform illumination in all fields of view, avoiding image edge blurring or loss of detail caused by uneven illumination. This greatly improves the quality and consistency of the acquired iris images, providing a strong guarantee for subsequent high-precision iris recognition.

[0086] The iris lens provided by this utility model has a total system length of 3.38mm and consists of only two lenses, making it easy to install. Its application is not limited to iris recognition systems but can also be used in miniature devices such as mobile phones. The working distance is between 400mm and 620mm, producing clear, uniform, and bright images with minimal iris image distortion. This lens can be paired with different models of CMOS sensors (metal complementary oxide sensors) to meet varying pixel requirements.

[0087] Embodiment 2 of this utility model also provides an iris recognition device, including the iris lens described above.

[0088] Obviously, the above embodiments are only examples for clearly illustrating the present application, and are not intended to limit the present application. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments are not required to be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. An iris lens characterized by, Comprise successively along the optical axis from the object side to the image side: A first lens, which is a convex-concave double-sided aspheric lens, is made of PC, and comprises: a first aspherical surface having a radius of curvature of 0.831 mm, a conic constant of -4.557, aspherical equation coefficients a2=0, a4=-0.445, a6=-2.11, a8=-9.275, a10=18.804, a12=-13.946 10 a first aspherical surface having a radius of curvature of 0.831 mm, a conic constant of -4.557, aspherical equation coefficients a2=0, a4=-0.445, a6=-2.11, a8=-9.275, a10=18.804, a12=-13.946 12 a first aspherical surface having a radius of curvature of 0.831 mm, a conic constant of a second aspherical surface with a radius of curvature of 0.37 mm, a conic constant of -1.035, aspherical equation coefficients a2=0, a4=-4.082, a6=9.51, a8=-20.14, a10=24.854, a12=-12.267, the distance of the vertex of the second aspherical surface from the vertex of the first aspherical surface being 0.39 mm; 10 a second aspherical surface with a radius of curvature of 0.37 mm, a conic constant of -1.035, aspherical equation coefficients a2=0, a4=-4.082, a6=9.51, a8=-20.14, a10=24.854, a12=-12.267, the distance of the vertex of the second aspherical surface from the vertex of the first aspherical surface being 0.39 mm; 12 ​ An aperture stop, which is 0.277mm away from the vertex of the second aspheric surface; A second lens, which is a convex-concave double-sided aspheric lens, is made of E48R, and comprises: The third aspherical surface has a radius of curvature of 0.573 mm and a conic coefficient of -2.

354. The coefficients of the aspherical surface equation are a2 = 0, a4 = 0.322, a6 = -1.169, a8 = 2.155, and a... 10 =-5.25, a 12 =1.575, and the distance between its vertex and the aperture stop is 0.1 mm; The fourth aspherical surface has a radius of curvature of -3.697 mm and a conic coefficient of -128.

561. The coefficients of the aspherical surface equation are a2 = 0 and a4 = 6.440 × 10⁻⁶. -4 , a6=0.96, a8=-5.197, a 10 =5.166, a 12 =0.352, and the distance between its vertex and the third aspherical vertex is 0.8mm; A parallel plate filter, which is made of K9 glass, and comprises: A first plate surface, which is 0.8mm away from the vertex of the fourth aspheric surface; A second plate surface, which is 0.2mm away from the first plate surface; An image sensing element, which comprises: A photosensitive surface, which is 0.81mm away from the second plate surface.

2. The iris lens of claim 1, wherein The clear aperture of the first aspheric surface is 0.6mm, the clear aperture of the second aspheric surface is 0.6mm, the clear aperture of the light stop surface in the aperture stop is 0.55mm, the clear aperture of the third aspheric surface is 0.56mm, the clear aperture of the fourth aspheric surface is 0.56mm, the clear aperture of the first plate surface is 0.6mm, the clear aperture of the second plate surface is 0.6mm, and the clear aperture of the photosensitive surface is 0.262mm.

3. The iris lens of claim 1, wherein, The total length of the iris lens is 3.376281mm, the focal length of the iris lens is 2.041765mm, and the F number is 2.

099.

4. The iris lens of claim 1, wherein, The working wavelength of the iris lens is 785nm to 900nm, and the main wavelength is 850nm.

5. An iris lens according to claim 4, wherein The refractive index of the first lens for the main wavelength of 850nm is 1.585, the refractive index of the second lens for the main wavelength of 850nm is 1.531, and the refractive index of the parallel plate filter for the main wavelength of 850nm is 1.

51.

6. The iris lens of claim 1, wherein, The field of view angle of the iris lens is 0°, 2.5°, 5°, and 7.5°.

7. An iris lens according to claim 6, wherein When the field of view angle of the iris lens is 7.5°, the root mean square diameter is 0.956μm, when the field of view angle is 5°, the root mean square diameter is 0.724μm, when the field of view angle is 2.5°, the root mean square diameter is 0.500μm, and when the field of view angle is 0°, the root mean square diameter is 0.405μm.

8. The iris lens of claim 1, wherein, The image sensing element is any one of a CCD image sensor and a CMOS imaging sensor.

9. The iris lens of claim 1, wherein, When the image sensing element is a CMOS imaging sensor, the pixel unit size of the CMOS imaging sensor is 1.12μm.

10. An iris recognition apparatus, characterized by comprising: The iris lens of any one of claims 1-9. The iris lens of any one of claims 1-9.

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