Optical Design And Manufacture Technique Of Iris Recognition Lens

With the development of science and technology,and the updating of smart-phones,the traditional identity recognition ways cannot meet people's highly requirement of information security.Thus,the biological recognition technology attracts human beings widely attention.According to corresponding reports,it reveals that fingerprint recognition and facial recognition have potential information leaking in practical application.However,iris recognition technology with the advantages of being protected,high stability and vastly anti-fake ability,to some extent,has overcome those shortcomings.It has attracted consideration interests over decades in the optical application fields.Applying iris recognition technology to Mobile Terminal makes it more and more vital to the innovation of technology and exploration for researchers.The primitive and the most key step in iris recognition technology is the obtainment of iris images,which has an directly influence on images quality and precision of recognition.In this paper,the main content contains the study of the obtaining images of iris on mobile devices,the design of a few iris recognition lens,and the summary of lens manufacturing technique.Specific contents as follows:Based on primary aberration theory,PW method was used to solve the initial structure of optical system.By analyzing the effect of optical system parameters on iris images quality,a large aperture and 2P aspherical structure iris recognition lens was designed optimally.The results show that the F number is 1.2,the total length is 4.1 mm,the field of view is 32°and the operation distance ranges 350 mm to 500 mm in the system.By the images quality assess and tolerance simulation analyze,a perfect images quality and high cost-performance lens were achieved,which can be used for further production.By using patent scaling method,a 3P aspherical iris recognition lens was designed optimally with F number 2.0,the field of view 32.6,and the total length 4.0 mm.When the lens work distance is between 300 mm and 350 mm,the perfect system MTF curve was attained;At1/2 Nyquist frequency,MTF of the fields from 0 to 0.8 are over 0.4,TV distortion is controlled within 1%,and comparative illumination is over 87%.Compared with 2P iris recognition lens,it has shorter total length,higher resolution,and better recognition precision.An iris recognition lens with phone facing camera function was designed optimally,Its F number is 2.4,the field of view is 61.2°,the total length is 4.45 mm.The system is a front facing camera in the visible wavelengths and a iris recognition lens in the near-infrared wavelengths,which were controlled and converted by IR transverter.According to the image quality evaluation,not only did the system satisfied the performance requirement of eight million pixels camera butalso the iris recognition.Taking the 3P iris recognition lens as an example,this paper describes the key points of structure design about the lenses,the barrel and the lens and finished the design of initial structure of 3P iris recognition lens.Meanwhile,by using the Light Tools software simulating and analyzing stray light of the structure,coating films were used to solving stray light in valid area and the structure was changed to solve stray light in invalid area.The summary of the lens manufacturing technique in the paper mainly includes mold structure designing,injection molding,and coating process.Besides,the paper introduced the coating process and analyzed the influence of coating parameters on the coating quality based on E48R material.