| 摘要 |
An optical device for measuring length or an angle between two objects has at least one recombination grid which receives partial beams of light, previously diffracted by a diffraction grid. The recombination grid contains two or more grid changes within a single graduation period (d). The ridges of the castellations of the recombination grid may be different in height, so that different phase diffraction angles may be created. The structure of the recombination grid makes it possible to produce diffracted partial beams having discrete phase angles, such as zero, positive one and negative one. Accordingly, each diffracted partial beam interferes with at least one other diffracted partial beam. The recombination grid structure also makes it possible to produce diffracted partial beams of a desired intensity. Accordingly, it is feasible to produce a plurality of diffracted partial beams, having different phase angles, wherein all diffracted partial beams have substantially the same intensity. The diffracted partial beams of discrete phase angles and desired intensity may be produced for a plurality of diffraction orders, such as positive 2 or negative 2.
|
