Lateral-Shift Infrared (LSI) Zoom Lenses for Guided Munitions

For missile guidance applications, there is a need for an infrared (IR) zoom lens that is compact, light-weight and environmentally rugged. In this program we will design an innovative IR zoom lens concept that uses lateral displacements of non-traditional optical elements to implement the zoom effect. The zoom lens consists, in part, of two lateral-shift, variable-focus lens groups. Our preliminary designs indicate that IR zoom lenses that employ lateral displacements may satisfy the size constraints and magnification ratios needed for missile guidance applications. We propose to design a f/4.5 LSI zoom lens with a magnification zoom ration of 4:1 that covers full fields of view ranging from 4.6 degrees to 18.2 degrees. The lens is designed to image the full field onto a focal-plane detector that consists of 480 x 640 pixels with 20-micrometer center-to=center spacings. Our goal is to keep the overall length of the zoom lens less than 150 mm, and to keep the diameter of the lens less than 75 mm. The proposed design represents a unique and innovative approach to infrared zoom lens design. As a result of this investigation, it is high likely that a new class of high performance, compact, infrared zoom lenses that area useful for missile guidance applications will emerge.