An infrared zoom optical system with a zoom range of 20:1 is designed based on long-wave 384 ×288 QWIP detector.The operating wavelength range is from 8 to 9μm,the F number is 3,and the focal length is continuously changeable form 18.5 to 367 mm.The system consists of a mechanically compensated zoom object and a secondary imaging system,including 6 lenses and 2 reflectors,and has the advantages of large zoom ratio,high resolution,small size and excellent image quality.The zoom optical system image quality i...