I was wondering if any other holographers have experienced this problem. The Sapphire 488-200 can be destabilized by noise/interference in the AC line. This shows up clearly in the expanded beam as an irregular wobbling or jittering. It looks identical to what would happen if the beam expander (spatial filter) was moving/vibrating. It would seem that the beam is changing direction very slightly when this happens (?). The expanded beam does not "glow" but wobbles or jitters in an irregular way. I know that vibration is not the cause, because when I plug another laser (a Genesis) into the same AC power strip, the wobbling starts, and when I unplug it, it stops. I think the wobbling also started once when the lab dehumidifier kicked on.
This might explain why I've seen occasional mode-hopping with this laser (banding in the image). I bought the following power conditioner, and will see if that helps.
https://www.amazon.com/dp/B003PJ6NPO?re ... asin_title