| 摘要 |
A rotation detection apparatus (2), comprising: a beam source (6) for emitting a beam of polarised light; a decohering arrangement (39) for eliminating or at least reducing the degree of coherence between first and second independent polarisation components of the polarised light to produce a decohered beam (108) of polarised light; a detector (46A, 46B) for outputting a signal in dependence on the intensity of light which is incident thereupon, the detector(46A, 46B) being arranged so that the decohered beam (108) of polarised light is incident upon it; a polariser (41) for location in the path of the decohered beam (108) of polarised light such that rotation of the polariser (41) relative to the decohered beam (108) of polarised light results in a variation of the intensity of light incident upon the detector (46A, 46B) from the beam source (6) and a corresponding variation in the signal output from the detector(46A, 46B); and a processor (48A, 48B, 48C) for detecting the relative rotation based on the variation of the signal output from the detector(46A, 46B). Other types of rotation detection apparatus are also described. |
