Development of large-diameter flat mesh-lenses for millimetre wave instrumentation

We present novel optics solutions based on metal mesh flat lenses which can be used to mimic a refracting lens. This approach removes the bulk of the dielectric materials (polyethylene or silicon) required for fast optical refracting systems. Additional attractive property of these lenses is that they filter out unwanted higher frequency radiation, they are easy to anti-reflection coat and they are extremely light. Measurements from 300mm diameter prototypes of both a Fresnel-type graded-index lens and a phase-delay type mesh-lens are presented.