A shutter assembly for an optical system includes a shutter housing that maintains optical alignments with adjoining parts of the optical system and a shutter mechanism that can be removed and replaced within the shutter housing without disturbing the optical alignments between the shutter housing and the adjoining parts of the optical system. The shutter mechanism can also include alignment features with the shutter housing for restoring the original optical alignment of the shutter mechanism with the adjoining parts of the optical system.