Design of infrared optical system with super-long focal length and dual field-of-view

A mid-wavelength infrared optical system with super-long focal length and dual field-of-view is designed in this paper. Based on the re-image configuration,this system can realize the zoom by axial motion of a lens along the optical axis. The design results show that this system realizes the zoom with a super-long focal length of 600- 1 500 mm,and the MTF of the central view is more than 0. 5 at the characteristic frequency of20 lp /mm of detector,which shows its optical performance approximates to the diffraction limit. This system can meet the requirement of military investigation for seeking and aiming at target in a long distance.