IMPROVED MEASUREMENT OF ANGULAR MOTION

摘要

The invention relates to an interferometer (1) for measurement of angular motion of a target (40). The interferometer comprises a source of a light beam (10), means for splitting the light beam from the source into at least first and second beams (22a, 22b) directed towards a target location and laterally spaced from one another. First and second retroreflectors (34a, 34b), positioned in the paths of the first and second light beams respectively following reflection from a target in the target location are also provided along with at least one detector for detecting fringes formed by interference of the first and second light beams following reflection from the first and second retroreflectors respectively.