Polarization-Grating Moiré*

Moiré-fringe patterns are formed when two grating structures with periodic variation of polarization are placed in contact. Such patterns are examined in this investigation. In particular, two kinds of polarization gratings are considered: the bipolar type, which alternately transmits light of two mutually orthogonal polarization states, and the one with a continuous variation in one dimension of the direction of the transmittance axis. Some characteristic features of this type of moiré are the increase of resolution compared to conventional moiré with absorption gratings, the arbitrarily variable contrast of the pattern, and the formation of a single-frequency moiré pattern. Experimental verifications are shown. Specific applications of the proposed polarization schemes are illustrated for polarization-type interferometers.