Meta-material interferometry systems and methods

An optical system, comprising:

• a first optical element comprising:
• a first substrate;
• a partially-reflective coating disposed on a first surface of the first substrate;
• a first meta-material layer positioned on or adjacent to a first surface of the first substrate and comprising a structure that defines a continuous phase gradient along a first direction parallel to the first surface of the first substrate, wherein a change in magnitude of the phase along the first direction is at least 2Ξ at a wavelength Σ;
• and
• a partially-reflective layer disposed on or adjacent to the first meta-material layer and on an opposite side of the meta-material layer from the first substrate;
• and
• a second optical element comprising:
• a second substrate;
• and
• a second meta-material layer positioned on or adjacent to a first surface of the second substrate and comprising a structure that defines a continuous phase gradient along a second direction parallel to the first surface of the first substrate,
• wherein the first and second optical elements are oriented so that the first and second directions are at a non-zero angle.