Dual Field Of View Infrared Zoom Lens Design

The target signal of the infrared optical system received is the infrared radiation which is based on the temperature of the detected object, thus the infrared optical system is not restricted by the ambient lighting conditions in the application of medicine, industry, military. The dual field-of-view infrared zoom optical system has the advantages of both the dual field-of-view optical system and the zoom optical system and has considerable application prospect. Compared with the fixed focal length optical system, dual field-of-view infrared zoom optical system can search the target in the large field of view using the short focal length lens and locate and track accurately the moving goal in the narrow field of view using the long focal length lens. Compare with the continuous zoom optical system, the dual field-of-view infrared zoom optical system can make the zoom lens group and the compensating lens group move along the optical axis without the cam gear. The Design and the manufacture is simple and the cost is low. For the infrared optical system, the F number decides the detectable distance directly, the greater the F number, the smaller the detection range, therefore the design of a dual field-of-view infrared zoom optical system with a small F number is necessary.In our paper the gaussian theory of the optical system and the third-order aberration theory was analyzed and a dual field-of-view infrared zoom optical system with a small F number was designed. The design is based on the640X480cooled infrared detector generated by the French company SOFRADIR and the pixel size is25μm, the detecting wave band is7.5-9μm. The initial structure of the dual field-of-view infrared zoom optical system was obtained by the Matlab, the design and optimization of the initial structure is through the Zemax. The design results show the F number of the dual field-of-view infrared zoom optical system is2.7, the focal length is42.5/290mm, the field of view range is±13.3°～±2°, the total length is270mm, the best image quality is at the focal length of42.5mm and290mm.