These mirrors, are convex plane mirrors used, to magnify the laser beam and focus the the laser beam light.
A Molybdenum Laser Mirror is an object that reflects light in such a way that, for incident light in some range of wavelengths, the reflected light preserves many or most of the detailed physical characteristics of the original light, called specular reflection.
These mirrors are used to guide the laser beam towards the lens so that it focuses the light of the laser beam.
A Golden Cover Laser Mirror is an object that reflects light in such a way that, for incident light in some range of wavelengths, the reflected light preserves many or most of the detailed physical characteristics of the original light, called specular reflection.