| 摘要 |
<p>A light source (9) emits light which has a coherence length corresp. to double the specific amt. and which gives rise to a first parallel light bunch directed for illuminating the end surfaces with parts of the parallel first light bunch. A component (17) causes at least parts of the light beams, which have been reflected against the end surfaces, to pass along the same path as a second parallel light bunch produced by the same light source, so that this has the possibility of interfering. Fixed placed components (47) are provided for observing a first interference pattern from the light radiations simultaneously reflected from the end surfaces together with the second light bunch. For producing the first and second parallel light bunches a semi-reflecting surface (17) is provided, against which a light beam from the source falls and is divided so that the one of the beams emitted from the surface gives rise to the first light bunch and the other emitted beam after right-angled reflection against a mirror surface (37) gives rise to the second light bunch.</p> |
