8mm～32mm Dual Band Zoom Security Lens Design

With the development of society and the improvement of people’s safety awareness,China’s security monitoring industry has been rapidly developed,and the application field of security lenses has been very extensive.However,in low light or even at night,whether the monitoring system can meet our requirements and whether it can obtain images with color effects to achieve intelligent and information-based monitoring.In response to the requirements of this application,this paper designed a dual-band constant large-aperture zoom security lens with a zoom ratio of 4 times.First of all,after finding and analyzing a large number of literature references,this paper introduces the structural form and compensation method of zoom lens,and explains the development status of zoom security lens at home and abroad.In this paper,four sets of lens groups are selected to form a positive group compensation zoom structure,the positive group compensation structure is analyzed by Gaussian theory,and the initial structure that can be referred to is selected through the requirements of various design indicators.Secondly,with the help of the optical design software Zemax,the initial structure is optimized to change the optical parameters so that it gradually meets our requirements,and the system aberration is effectively corrected by editing the evaluation function.After repeated optimization of the structure,the design of the system was finally completed by a total of 13 glass lenses from four lens groups,including 2 even aspherical lenses.The focal length range is8.0mm to 32.0mm,the F number is constant to 1.6,and the Sensor image receiver of 1/1.8 inch is used.The small size of the lens is completely in line with the current mainstream trend in the market,and the final optical system total length is less than 62 mm.The imaging quality of the system meets the requirements,the point on the optical transfer function is greater than 0.3 at167 lp/mm,the point outside the axis is greater than or close to 0.2 at 167 lp/mm,the optical distortion of the system is less than 10%,and the out-of-focus amount of near-infrared light 850 nm is less than 20 μm.Finally,the zoom cam curve selection Zemax point drawing method to get,the advantage of choosing this method is not only to get the zoom cam curve,but also to optimize the image quality of each focal length of the system,to ensure the imaging quality of the entire zoom process,this paper takes a total of 13 focal points to draw the cam curve,the cam curve is smooth and smooth and there is no mutation at the inflection point,the overall change is more natural,while the mechanical structure is smooth and less resistant during the movement.Finally,the tolerance analysis of the system is carried out,and the tolerance range of each error is set,and it can be seen through data analysis that the tolerance range of the system is small and needs to be further improved.