Radial Shearing Interferometer Based on a Cosinusoidal Zone Plate

A simple and compact radial shearing interferometer (RSI) based on a cosinusoidal zone plate (CZP) is proposed. The CZP can modulate both phase and amplitude, it has two foci, so as the nominal plane beam under test passes through the CZP, it is diffracted into two parts, i.e., a converging beam and a diverging beam. Then, the two beams can be considered as the compressed beam and the expanded beam in the RSI, respectively. A charge-coupled device detector located in the vicinity of the CZP records the interference pattern. This RSI needs only a single zone plate and therefore can be made very compact. The experiment validates the correctness of the proposed method. With the compactness and stability, the presented interferometer is expected to be used in the detection of moving objects and dynamic processes.