| 摘要 |
<p>An interferometer system is used for high resolution measurment of angular displacement. Light from a laser diode 1 passes though a linear polariser 2 and is then split by a non-polarising beam-splitter 3 into two beams 1a and 1b, each linearly polarised and carrying the same temporal phase information. The polariser is set so that the state of polarisation is initially aligned with one of the axes of a polarising beam-splitter 5. One of the beams 1b enters the polarising beam splitter 5 where it is split into two further, orthogonally polarised beams 1c and 1d which are reflected by mirrors 6 and 7. The two beams are recombined in the polarising beam splitter 5 with a phase difference due to the difference in path lengths taken by the two. The recombined beam passes though a polariser 8 set at 45 degrees to the axes of the polarising beam splitter 5 and then observed by a detector 9. From the detected intensity the angular displacement R of the polarised beam-splitter can be calculated.</p> |
