According to the characteristics of the terminal guidance phase of air-to-air missiles,a scheme of common aperture IR-imaging/laser-ranging compound seeker optical system is proposed,which can implement precise detection and tracking of typical aerial targets.The seeker design scheme includes two modes:passive IR imaging mode and active laser ranging mode.The former is used for target searching and acquisition,and the later is used for obtaining precise missile-target range information.In the compound seeker,the two modes share the common optics system.The compound seeker can not only meet the requirements of the large field-of-view for target searching and acquisition,but also improve the guidance accuracy of the proportional guidance by using the precise range information.