ELLIPTICAL POLARIZERS, TAGS AND IDENTIFICATION SYSTEMS USING FREQUENCY SELECTIVE SURFACES
First Claim
1. An optical combination, comprising:
- a substrate;
a linear polarizer on said substrate, anda elliptical polarization filter comprising a first frequency selective surface (FSS) on said linear polarizer, said first FSS comprising least one periodic pattern of spaced apart electrically conductive lines having a sub-wavelength line-to-line spacing, said lines including at least one subwavelength geometrical feature, said pattern being operable to impose a phase differential for one orthogonal linear polarization state relative to the other linear polarization state for electromagnetic radiation having a wavelength from 400 nm to 1 mm.
1 Assignment
0 Petitions
Accused Products
Abstract
An optical combination includes a substrate, a linear polarizer on the substrate, and a first frequency selective surface (FSS) based elliptical polarization filter on the linear polarizer. The first FSS comprises at least one periodic pattern of spaced apart electrically conductive lines having a sub-wavelength line-to-line spacing orientated along a first axis. The pattern is operable to impose a phase differential for one orthogonal linear polarization state relative to the other linear polarization state for electromagnetic radiation having a wavelength between 400 nm and 1 mm, such as 1 μm to 12 μm. An identification system and associated method for identifying objects includes at least one tag having encoded information attached to the surface of an object to be identified, wherein the tag includes a first FSS-based elliptical polarization filter which provides the encoding. A remotely located receiver including a second FSS-based elliptical polarization filter and a linear polarizer optically coupled to the second filter is operable for differentially attenuating the first and second orthogonal polarization states allowing a determination whether the intensity pattern corresponds to the encoded information.
-
Citations
31 Claims
-
1. An optical combination, comprising:
-
a substrate; a linear polarizer on said substrate, and a elliptical polarization filter comprising a first frequency selective surface (FSS) on said linear polarizer, said first FSS comprising least one periodic pattern of spaced apart electrically conductive lines having a sub-wavelength line-to-line spacing, said lines including at least one subwavelength geometrical feature, said pattern being operable to impose a phase differential for one orthogonal linear polarization state relative to the other linear polarization state for electromagnetic radiation having a wavelength from 400 nm to 1 mm. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. An identification systems comprising:
-
at least one tag having encoded information attached to the surface of an object to be identified, said tag comprising a first elliptical polarization filter, said first elliptical polarization filter comprising a first frequency selective surface (FSS) disposed on said surface, said first FSS comprising least a first periodic pattern of spaced apart electrically conductive lines having a sub-wavelength line-to-line spacing, said lines including at least one subwavelength geometrical feature, said pattern being operable to receive incident radiation having a wavelength between 400 nm and 1 mm and output radiation having a phase differential for one orthogonal linear polarization state relative to the other linear polarization state; a receiver remotely located from said tag operable for differentially attenuating said first and said orthogonal polarization states comprising a second elliptical polarizing filter coupled to receive said output radiation, said second elliptical filter comprising a second FSS comprising least one periodic second pattern of spaced apart electrically conductive lines having a sub-wavelength line-to-line spacing, said lines including at least one subwavelength geometrical feature, and a first linear polarizer optically coupled to said second elliptical polarizing filter; a photodetector optically coupled to said linear polarizer for generating an intensity pattern, and a processor operable for determining whether said intensity pattern corresponds to said encoded information. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25)
-
-
26. A method for identifying objects using a remotely located receiver and at least one polarizing tag comprising a frequency selective surface (FSS) comprising a first and at least a second different elliptical polarization emitting portion disposed on a surface of an object to be identified, comprising:
-
responsive to radiation received at or emitted from said surface, said tag emitting encoded information by emitting a first elliptically polarized emission from said first portion and a second different elliptically polarized emission from said second portion, and differentially attenuating one of said first and said second elliptically polarized emission to create a differential intensity pattern between said first and said second polarization emitting portion when viewing radiation emanating from said surface received at said remotely located receiver, and determining whether said intensity pattern corresponds to said encoded information. - View Dependent Claims (27, 28, 29, 30, 31)
-
Specification