Design&Research Of High Ratio IR Continuous Zoom System

Infrared optical systems have advantages of a strong penetrating power at night, identifying camouflage ability, passively receiving the infrared radiation, good for hiding, less susceptible to interference, etc., zoom optical system can achieve either within the wide field to search target or within a small field to track target, so infrared zoom optical system is widely used in scientific research education, daily life as well as land, sea and air military in military field. In some particular areas of work, in order to enable a greater range of searching and tracking target that get more detailed useful information, it is necessary to improve the system of zoom ratio, so designing with high zoom ratio, compact structure, low complexity and light weight infrared continuous zoom optical system becomes a hot spot.The paper describes the basic theory of the zoom system, as well as some characteristics of infrared optical system design, and on this basis using ZEMAX optics design software, A ten times LWIR continuous zoom optical system is designed for uncooled320x240detector, the system had a large zoom ratio, large relative aperture, image quality higher, etc., system imaging quality requirements was met; A ten times MWIR continuous zoom optical system is designed for cooled320x240staring focal plane array detector. The system uses mechanical positive compensation zoom system, by introducing reasonable aspheric and diffractive surface, realizes100%cold stop efficiency by secondary imaging system, two common infrared optical materials of silicon and germanium are used, it achieves continuous zoom during the range of20mm to200mm, it has the advantages of a smooth curve zoom, less number of lenses and smaller F#, it can meet the zoom optical system requirements.