PHASE ADJUSTING DEVICE OF MOIRE PATTERN

摘要

PURPOSE:To facilitate the phase adjustment of a moire pattern by forming the radial lattice of an index scale with the phase of a part thereof shifted by a quarter of a pitch with respect to the radial lattice of the rest of the part. CONSTITUTION:A radial lattice 2 is formed on a main scale 1. A radial lattice 4a of a pattern the same with that of the main scale 1 is formed on a part 3a of an index scale 3, while a radial lattice 4b which is displaced by a quarter of a pitch (P) at the boundary 5 between the part 3a and the part 3b of the index scale with respect to the radial lattice formed in the part 3a and has a pitch: P+ or -P/4 is formed in the other part 3b. A moire pattern stepped along the boundary 5 is formed by the combination of the main scase 1 and the index scale 3 when the scales are illuminated by a light source 9. The phase of the moire pattern is adjusted by moving the index scale 3 so as to arrange the moire patterns parallel with each other.