Yea, I know it has an optical sensor as it has to be aligned often, and it does cause problems when cutting translucent acrylic as it has to be focused with a solid piece first, then you have to quickly swap the acrylic before cutting starts. It is an ancient 1980s laser cutter with a parallel printer port. The laser seems to be a lot weaker than 30w too, but unfortunately it isn't mine to repair. Hopefully we will get a new one soon, I usually end up having to stay an hour or so at the end of the day just to finish cutting some acrylic.