| 摘要 |
<p>An interferometer for measurement of displacement utilises circular polarisation of the two beams in opposing directions. The beams are processed and analysed to obtain two fringing signals with a phase difference of 90 deg. The average intensity is zero. Monochromatic light (1a) from a laser (1) is divided (2) into a measurement beam (3) directed towards a moving reflector (4) and into a reference beam (5) directed towards a fixed reflector (6). Returned beams (3a, 5a) pass into a divider (2) to become a single beam (7). This is directed by a mirror (8) into a divider (9) and the beams (21, 12) are detected (20, 13, 11) after analysis (16, 15, 22). Detected beam signals are amplified for subtraction and further processing for display.</p> |
