Determination of small angular displacement by moiré fringes of matched radial-parallel gratings.

We investigate the properties of the moiré fringes of matched radial-parallel (MRP) gratings that are useful for the fine visual indication of angular displacements. Moiré patterns formed by overlapping two different MRP gratings of angular pitches, P(theta) and P(theta)? (

Determination of the absolute order of shadow moiré fringes by using two differently colored light sources.

We present a simple method of determining the absolute order of shadow moiré fringes by using two differently colored light sources. This technique is based on the periodic color structures generated by superimposing two moiré patterns with different colors.