Modulated Light Beam Communications System
Original Publication Date: 1978-Jul-01
Included in the Prior Art Database: 2005-Feb-21
This article describes an amplitude modulated light-beam communications system. Light from a laser 1, illustrated in the drawing, is directed to a beam expander 2 which expands the beam. The expanded beam illuminates a cylindrical lens 3 which emits a narrow elongated beam of a single frequency. This beam illuminates a stack of dove prisms 4. The stack is made up of alternating movable and fixed prisms. Thus, the angular magnification of this stack is a function of the number of movable prisms contained therein. The single frequency light emanating from the last prism in the stack is directed to a blocking screen 6 which includes a slot and, therefore, modulates the amplitude of the light as the beam from the dove stack is angularly displaced by movement of the movable dove prisms.