A near-field optical head has a planar substrate having a first surface, a second surface disposed opposite to the first surface, and an inverted conical or pyramidal hole extending through the first and second surfaces. The conical or pyramidal hole has at least one fine aperture formed at an apex thereof...http://www.google.de/patents/US7599277?utm_source=gb-gplus-sharePatent US7599277 - Near-field optical head having tapered hole for guiding light beam
