Double-wedge prism scanner for application in thermal imaging systems.

Abstract

In this paper, double-wedge prisms, also known as Risley prisms, and composed of two wedge prisms, are presented with assemblies in four configurations. In the double-wedge prism scanner, the center of the two wedge prisms is aligned with the optical axis; thus, the optical system and mechanical structure are simple. In contrast to conventional scanners, its assembly is compact, robust, and insensitive to vibrations and wobbles. However, the relationship between the deviated and rotated angles is not linear, and the trajectory of the scan pattern is nonrectilinear; therefore, double-wedge prisms have rarely been used in imaging systems as a one-dimensional scanner until now. This study presents the optical characteristics of double-wedge prisms and proposes methods to solve the problems mentioned above. The experimental results demonstrate that the double-wedge prisms can be used in an imaging system as a one-dimensional scanner.