Optical Design And Evaluation Of A Zoom Security, Day And Night Con-focal System

Security industry in our country has entered a stage of rapid development, at thesame time, security monitoring camera system has also been widely used in roadtraffic, hospitals, airports, libraries and other public places. And optical lens is one ofthe important part of the security monitoring system, which can transfer image tosensor, then the sensor gives us the real-time information of the monitoring objectsafter image and signal processing. So the image quality of the security camera has agreat influence on the entire monitoring system. In recent years, with the constantinnovation of the sensor technology, image quality has been greatly improved, and thesecurity optical lens also develop from SD to HD, from prime lens to zoom lens, fromsingle imaging of visible light to con-focal imaging of visible light and Infrared light.Mega-pixels, day and night zoom lens will become the main requirements of thefuture security market. At present, the country has extensively produced and appliedprime lens of mega-pixels, but the image quality of corresponding zoom lens is notgood as the prime lens, so the HD zoom lens may introduce high-order aspheric in theprocess of optical design in order to improve its imaging quality, which can furthercorrect and balance the residual aberration of each state of the continuous zoomsystem and achieve the purpose of improving image quality.In this paper, it firstly introduces the history of the security monitoring lens, andanalyzes the classification, principle of zoom security system and the advantages anddisadvantages of all kinds of security zoom systems on the basis of a large number ofthe domestic and foreign literature. Then it also specifically analyzes the general ruleof the zoom optical system of two groups of single zoom group and singlecompensation group to pave a way for the follow theoretical derivation and designexample. Finally, this paper complete the design of a optical system of continuouszoom on the basis of the introduction of a high-order aspheric lens, whose zoom rangeis2.8-12mm, maximum relative aperture is1/1.6, image is two million pixels, and itcan achieve switch at day and night. This camera belongs to manual zoom system oftwo groups, in other words, a zoom group and a compensation group, and it does notneed track to locate the lenses. It meets the requirements of light structure, simpleoperation and low cost, at the same time, its built-in IR infrared function can realize real-time monitoring for24hours.This paper finally tests and analyzes various properties of this lens with aprofessional testing software imatest, which includes resolution test, relativeillumination test, color reduction test, distortion test, etc., and actually shot the endrenderings of the state of wide-angle and telephoto during day and night. The testresults and the real effect show that this security camera can basically meet therequirements of design and employment.