Strahlengang im Resonator
<a href="https://en.wikipedia.org/wiki/de:User:Herbertweidner" class="extiw" title="w:de:User:Herbertweidner">Herbertweidner</a> at <a href="https://en.wikipedia.org/wiki/de:" class="extiw" title="w:de:">German Wikipedia</a>
selbst gezeichnet