| 摘要 |
<p>Optical apparatus for measuring the topographic properties of a surface uses a beam of coherent radiation which is split by a beam splitter (2) into a reference beam and a probe beam. The probe beam is modulated by a Bragg cell which is switched at two frequencies (φ1, φ2). A detector (6) recombines the components of the probe beam after reflection to produce a plurality of tone bursts the phase differences of which correspond to variations in the surface topography.</p> |
