Fabrication methods of a Luneburg lens
Methods of forming Luneburg lenses and Luneburg lenses formed from same are provided. One method includes providing a spherical core formed of a material with a substantially uniform dielectric constant from a center of the spherical core to an outer surface of the spherical core. The method further includes forming a plurality of holes that are substantially uniform in size and symmetrically located about the center of the spherical core. The method further includes forming an at least one outer layer that is substantially spherical by winding a filament formed of a low-loss material around the spherical core.
1 . A method of forming a Luneburg lens, comprising:
providing a spherical core formed of a material with a substantially uniform dielectric constant from a center of the spherical core to an outer surface of the spherical core;
forming a plurality of holes substantially uniform in size and symmetrically located about the center of the spherical core; and
forming an at least one outer layer that is substantially spherical by winding a filament formed of a low-loss material around the spherical core.
2 . The method according to claim 1 , wherein winding the filament is conducted by 3D printing.
3 . The method according to claim 2 , wherein the low-loss material of the filament comprises at least one of polylactide or polyethylene terephthalate glycol.
4 . The method according to claim 1 , wherein the low-loss material of the filament is formed of an optical fiber.
5 . The method according to claim 4 , wherein the optical fiber includes an outer polymer coating and an inner glass core.
6 . The method according to claim 1 , wherein winding the filament is conducted such that at least one of the at least one outer layer defines a plurality of coils that do not cross one another.
7 . The method according to claim 6 , wherein each coil is substantially in abutting relationship with adjacent coils.
8 . The method according to claim 6 , wherein each coil is substantially uniformly spaced from adjacent coils.
9 . The method according to claim 1 , wherein each of the holes are formed to have a plurality of segments and each segment defines a cross-section, each cross-section larger than an adjacent cross-section in a direction from the center of the spherical core towards the outer surface of the spherical core.
10 . The method according to claim 9 , wherein each segment has a length and the cross-section of each segment is substantially uniform along the length.
11 . The method according to claim 10 , wherein the plurality of segments includes three or more segments.
12 . The method according to claim 10 , wherein each hole is formed by drilling with a stepped drill bit.
13 . The method according to claim 1 , wherein the material of the spherical core is substantially solid and homogeneous prior to forming the plurality of holes and the substantially uniform dielectric constant is between about 2 and about 5.
14 . The method according to claim 13 , wherein the material of the spherical core includes polytetrafluoroethylene.