Multibeam optical and electromagnetic hemispherical/spherical sensor

Abstract

An optical spherical Luneburg lens is described which is also useful for millimeter wave and microwave operation, which can provide a multitude of simultaneously acting receiving beams over a hemispherical or spherical field of view. When used in conjunction with surface mounted optical/radio frequency pickup elements, the lens can be employed in a passive target detection system of unique field of coverage and sensitivity. The lens comprises a center sphere of refractive index of approximately .sqroot.2, around which are arranged in concentric shells of aerogel material. The aerogel material of the respective shells is fabricated to obtain a particular index of refraction approximately equal to (2-(r/r.sub.0).sup.2).sup.1/2, where r is the radius of the shell and r.sub.0 is the radius of the lens assembly. The lens can be employed in a system providing dual mode simultaneous optical and radio frequency operation with a single aperture. Its multibeam simultaneous detection capability can provide an input to advanced digital signal processors to perform automatic image and pattern recognition for commercial and military sensor systems. It may also be used as an active sensor using optical or radio frequency energy.