Only from the principle analysis, the focus should be behind the galvanometer, because if the light diverges before and after the galvanometer and cannot be concentrated, the marking effect will definitely be bad. In addition, if the focus falls on the galvanometer, the membrane of the galvanometer is easily damaged due to too strong light intensity. It stands to reason that the focus position falls on the target.

The special requirements of galvanometer are related to wavelength. If it is a solid-state laser with 1064 nm band, it is mainly because the coating has high reflectivity and high damage threshold, and it is easy to keep a clean environment.

Theoretically, it is best to ask the manufacturer for details.