Recently I've visited the the Deutsches Technikmuseum and the Science Center Spectrum in Berlin. I can really recommend both for you and your family. My kids enjoyed the science center with lots of hand-on experiments explaining physics. The section about the optics was extremely cool and there was a demonstration explaining how the optical fibers work. I tried to take a photo but it was pitch dark:
At the next station you can manipulate prisms and lenses:
Highly recommended if you visit Berlin.