Passive millimeter wave differential interference contrast polarimetry

A method, comprising:

• receiving a first radiation flux from a first object patch and a second radiation flux from a second object patch;
• directing the first radiation flux and the second radiation flux along first and second axes to first and second antennas, respectively;
• and
• based on the radiation fluxes received at the first and second antennas, determining at least one polarization difference between the first object patch and the second object patch.

A millimeter wave imaging system, comprising:

• a mirror defining an aperture stop of diameter D and situated so as to form an image of an object;
• an axicon situated to displace image portions of the image formed by the mirror;
• antennas situated configured to receive radiation portions associated with respective displaced image portions;
• and
• a radiometer coupled to the antennas and configured to produce an output corresponding to a polarization difference between the image portions.

A method, comprising:

• obtaining image patches associated with first and second object patches;
• adjusting an image patch separation so as to conform to an antenna spacing;
• and
• directing radiation associated with the first and second image patches to a first and a second antenna, respectively;
• and
• based on the directed radiation, determining at least one polarization difference between the first image patch and the second image patch.