Interferenz von Licht verschiedener Frequenz
A new method of rotating a photografic screen allows the recording of the moving interference pattern produced by two light beams of different frequency. The method is demonstrated with frequency differencies up to 3 · 103 sec−1. It probably can be applied up to 108 sec−1 by using intense laser light.The interference between waves with different frequencies demands a generalisation of the concepts of partial coherence. This is performed by defining a general function of mutual coherence, which now includes also the moving interferences. The new definitions of the general degree of coherence and of the general visibility are applied to the demonstrated example.