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 .mu.m to 12 .mu.m. 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.