Moiré Fringes as Visual Position Indicators

A summary of the main known forms of moire fringes for visual metrological applications is given. To observe and track displacements of a moving fringe in a conventional moire system presents certain difficulties, as the individual fringes have no distinctive character. New types of moire fringes were found and are discussed, where a recognizable unique fringe indicates an also unique position of a grating, displaced relative to its stationary counterpart.