in order to get an idea about the part/subsystem causing the RF power modulation while sweeping the VCO frequency i changed the length of the cable to the AOM. I decided to just extend the existing cable using a cheap SMA cable, not one of those semi-rigid ones. Now i thought due to more losses, low quality cable, longer, more connection etc. the shifted power should be less, but it seems to be the opposite, see screenshot. The purple curve is the transmitted power through the refcav, red the VCO input signal, the rest unimportant. On the left third the old cable, then a short break where i extended the cable, the center part with the longer cable, another short break and then with the original length. First i thought it's some aligment related thing, touching the cable, changing the alignment of the AOM etc. But it's not. The PD behind the curved mirror (not shown) shows exactly the same. Any ideas?