Design Of Optical Lens Based On Iris Recognition

With the increasing application of identity recognition,traditional identity recognition can no longer meet the market demand in terms of accuracy and security.Due to the continuous improvement of technology,biometric technology is widely known because of its trustworthy and accurate recognition characteristics.Compared with common biometric technologies,researchers found that the characteristics of iris recognition accuracy and security are particularly outstanding.Therefore,iris recognition technology has become a research hotspot in recent years.Among them,image acquisition is the first step in iris recognition.The performance of the iris recognition lens design directly affects the quality of iris image acquisition,and thus affects the accuracy of iris recognition.The existing commonly used lenses for iris recognition have a short working distance and a narrow working range,resulting in poor availability of iris recognition.In this paper,two iris recognition lenses are designed to solve the short working distance of iris image acquisition.Specific contents as follows:(1)A mobile phone lens was designed using ZEMAX software.After modification and continuous optimization,a lens that could be used for iris recognition was obtained.This lens has four lenses with a total of eight surfaces,with a total length of 4.09 mm and an F value of 2.4.The design results show that the modulation transfer function(MTF)at the 1/2 Nyquist frequency at the intersection of the meridian and sagittal is greater than 0.4,the distortion is within 0.6%,and the illumination uniformity is good.It can be known from the image quality evaluation and tolerance analysis that the system has small optical distortion,large working distance,excellent image quality and stable performance,and meets the processing requirements of the iris recognition lens.(2)A zoom lens was designed using ZEMAX software.The F-number is 2.9,the focal length range is 5-25 mm,and the total length is 103.87 mm.The advantage of this lens over the fixed-focus iris recognition lens is that it can clearly image in a long working range,instead of only aclearly image at a fixed focal length like a fixed-focus lens.The farther away from this focal length the worse the image quality,the overall imaging effect of the zoom lens is better in the working range of 100?500mm.At 166lp/mm,the MTF of the lens center field of view at different focal lengths is greater than 0.2,making the iris recognition image acquisition process more flexible.At the same time,the distortion is less than 1% at the short focus and the long focus,which ensures that the collected iris texture is not deformed.Finally,a curve fitting is performed on the amount of movement of the zoom group and the compensation group.From the fitted graph,it can be seen that the curve is stable and smooth,which ensures the smooth zooming process of the zoom system.