Laser resistance and stress-free mirrors, windows, polarizers, and beam splitters up to 400 mm×400 mm are required for the construction of the series SG facilities. In order to improve the coating quality, a program has been in place for the last ten years. For the small-aperture pick-off mirror, the laser-induced damage threshold (LIDT) is above 60 J/cm2 (1064 nm, 3 ns), and the reflected wavefront is less than λ/4 (λ=633 nm). The Brewster-angle polarizing beam splitter (Φ50×10 mm) shows the be
