Fresnel zone plate

摘要

A Fresnel zone plate is provided for encountering incident light having a wavelength. The Fresnel zone plate has a focal length and a wafer including alternating transparent and opaque zones, and a mourning surface. A plurality of silicon nanowires extend into opaque zone of the wafer. A mechanically stretchable tuning structure is mounted to the mounting surface such that stretching of the tuning structure varies the focal length of the Fresnel zone plate.

主权项

1. A Fresnel zone plate for encountering incident light having a wavelength, comprising:
a substrate defining a generally planar surface; a first set of rings radially spaced about a central axis along the surface of the substrate, the first set of rings being transparent; a second set of rings radially spaced about the central axis along the surface of the substrate, each ring of the second set of rings including a surface lying in a plane perpendicular to the central axis and being opaque; and a plurality of silicon nanowires extending into at least one of the surfaces of the second set of rings, the plurality of silicon nanowires;
having lengths in the range of 1 micrometer to 6 micrometers; andbeing randomly distributed in the at least one of the surfaces of the second set of rings;wherein each of the plurality of silicon nanowires extending along a corresponding axis generally perpendicular to the plane and being spaced from an adjacent silicon nanowire by a distance less than the wavelength of the incident light.