It is well known that optical dielectric coatings show a change in performance when altering the environmental condition from air to vacuum. Evacuating or venting a set-up will shift the spectral characteristic and also the damage behavior of the specimen. With respect to the spectral shift it has been observed that dense dielectric coatings manufactured by Ion Assisted Deposition and Ion Beam Sputtering do not show this modification. This work was performed to investigate AR coatings of different deposition processes to determine whether the LIDT of dense layers can also be kept stable in vacuum. It was found that the damage threshold of these dense coatings is also stable in an evacuated environment.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.